The "Ten Best Home Improvements" is an oft-cited list in newspapers and shelter magazines. But what about the worst improvements?

Since the bad ones rarely rate a mention, here's a look -- realizing, of course, that we're not talking about personal taste, need or comfort. This list, rather, comes from a strictly return-on-investment point of view.

-- Swimming pools. Pools top everyone's list of don't-do-its, if only because not everyone wants one. So if you put a pool in your backyard, you are eliminating better than half your potential market, and you haven't even put up a "For Sale" sign yet. You want to appeal to the largest buyer pool possible, no pun intended.

Beyond that, there's the cost. The experts maintain that unless you are in a neighborhood where pools are an anticipated amenity, not an unexpected one, you'll be lucky to recoup half the cost. Ditto for basketball and tennis courts.

Doug Rogers of Century 21 Millennium in Pineville, La., recently went on a listing appointment in a subdivision of $200,000 houses. Once he got there, the owners "couldn't wait to show me" their new $45,000 pool. And, of course, they wanted to ask $260,000 for their otherwise ordinary house.

At closing, though, the pool netted them just $7,000, which means they took a loss of $38,000.

Better to join a country club or perhaps the local YMCA. In Virginia, where pools are good only three months out of the year, John Statton of RE/MAX Action Real Estate in Mechanicsville says you can join a local pool for $300 a year -- without the increase in homeowners' insurance that owning a pool brings.

It's "weird but true," says Northern California agent Lloyd Binen. "In Silicon Valley, as many people take pools out as put them in."

-- Converting a garage. You might not want to park your family jalopy under covered space, but the next owners may. And once you seal off the garage doors or remove them altogether, you're done.

And let's face it: Garages make lousy dens, if only because they're cold. You have to insulate and run new ductwork to carry conditioned air to the space. That's likely to put too much of a load on your HVAC system, which was probably sized for the original house.

Phil Hopkins of Desert 2 Mountain Realty in Payson, Ariz., tells of an investor he knows who has flipped some two dozen houses in the last three years: His best returns are on those with converted garages. The investor buys low, turns the garage back into a garage, and makes a killing.

The people who owned Wallingford, Conn., agents Pat and Wayne Harriman's place before them converted the one-car garage into a master bedroom. "It's a huge room, and very nice, but no garage is a point of contention amongst buyers here," they posted on ActiveRain.com, the real estate chat site where "worst improvements" is a frequent topic. "It will come back to haunt us when we go to sell."

-- Granite countertops. There tends to be wide disagreement on this one. However, the majority of ActiveRain bloggers seem to believe that it's a poor investment to top your counter with granite in a Formica neighborhood.

Thomas McCombs of Century 21 HomeStar in Akron says that in five years, granite will be "the first thing that marks a home as being outdated." But Travis Parker of Team Linda Simmons in Enterprise, Ala., looks at it the other way. Newer homes feature granite, so owners of older homes have to keep pace or drastically reduce their asking prices, he says.

-- Home office. Converting that extra bedroom you never use into an office, complete with bookshelves and other permanent built-ins, is great if you work at home, but most people still don't. In fact, most people would rather have the extra bedroom, the ActiveRain contributors maintain.

-- Over the top. Updates are one thing, but don't overdo them. Bringing your post-WWII bathroom into the 21st Century will increase your home's market value, but adding a steam shower and carved marble tub probably won't, says Anthony Razhas of Real Estate eBroker in Carlsbad, Calif.

Remember, your idea of "luxury" may be a buyer's idea of "bizarre." Monique Ting of INET Realty in Honolulu once showed a house with a hot tub in the middle of the family room. "My clients were not impressed," she says.

-- Anything too personal. Highly personalized spaces -- a wine cellar, koi pond or darkroom, perhaps -- are not likely to bring a high resale value, says Michelle Roberts of Coldwell Banker Sea Coast Realty in Wilmington, N.C. "They appeal only to folks with the same likes as you," she says.

"Save your special things for the house you are going to live in until you die," advises Rick Snow of First Choice Realty in El Paso, Texas. Jane Peters of Power Brokers International in Los Angeles agrees. "If you upgrade," she warns, "upgrade for your own pleasure, not with the idea you are going to make a killing."

Many owners make improvements thinking they will add value, but Allen Deaver of Sky Realty calls them "Free Gift With Purchase." Case in point: Deaver's own brother.

"He built a beautiful water garden that covered almost half an acre," the Kyle, Texas, agent says. "When he got ready to sell, he was sure the water garden would make a big difference. The day after the sale, the new owner had a dump truck bring a load of dirt to fill in the water garden."

-- Bright colors. Painting is a great way to spruce up a house, but leave the bold, bright colors to the next owner. If would-be buyers have to re-paint your orange walls, they'll offer less -- often much less. Better to stick to neutral shades.

-- Do-it-yourself. If you don't have the tools and know-how, leave the job to the experts, no matter how easy it looks on paper. Amateur work sticks out like, well, a sore thumb.

-- Obtain a permit. This goes hand-in-hand with not doing it yourself. Most places these days require a permit for almost everything, so if one or more are necessary, make sure you or your contractor obtain them. Otherwise, you or your buyer may have to redo the work so it meets the local code requirements, and that devalues your house.

Do you know the difference between implied and written warranties? How about being preapproved for a mortgage as opposed to prequalified? Or an appraisal vs. a broker's price opinion vs. a home inspection?

Many neophyte homebuyers don't know, so here's a quick tutorial:

-- Warranties. These are promises that the seller makes to stand behind his product. Builders typically guarantee their homes to be free of defects in workmanship and materials. Federal law requires that all warranties be available for buyers to read before they sign a contract.

Generally, the warranty against poor workmanship -- loose floor tile, for example -- is for a year. Coverage for the plumbing, HVAC and electrical systems usually lasts two years, and protection against structural defects that render the house unsafe typically runs for a decade.

Some warranties are backed only by the builder. In other cases, the builder purchases the warranty from an independent company that assumes responsibility for claims. But all define exactly what's covered and the responsibilities of both the builder and the buyer in resolving problems.

Additionally, every state has an implied warranty that can last as long as four years, depending on the state. So even if you don't receive a written warranty from the builder, you may be protected under state law. Or if you have just a one-year written warranty, you may be protected longer under your state's implied warranty law. Many states extend implied warranties to second, third or even later buyers.

If you are buying an existing home, either you or the seller can purchase a one-year "warranty" to cover the building's systems and appliances. But "warranty" in this case is a misnomer; these are service contracts with deductibles and other limitations.

In either case, new home or used, never rely on so-called spoken warranties, which are promises made orally by a salesman. Always get it in writing. Otherwise, the promise may prove to be an empty one.

-- Loan approvals. Getting prequalified is the first step in the mortgage process. You supply the lender with basic information about how much you earn, how much you owe and your other assets. The lender, in turn, supplies a letter saying that you are qualified to borrow up to a certain amount, which should determine the price range in which you shop.

Generally, real estate agents will not show property to anyone who is not prequalified in this manner. But prequalification letters are riddled with loopholes that allow the lender to escape for any number of reasons. The real promise is when you are preapproved.

With a preapproval, the lender has had time to review and verify the information you supplied in your loan application. If you are preapproved, you are good to go with one condition -- whether the house you choose will appraise at a value high enough for the lender to recoup its investment should you default on your promise to pay.

-- Appraisals. Here's where things really get tricky, so let's start with the difference between a home inspection and an appraisal.

An inspection is a complete, top-to-bottom examination of the house by a third party to make sure all systems are in working order and to spot any issues that may need repair. It has nothing to do with value, only the condition of the property.

An appraisal, on the other hand, is strictly a valuation. While it takes condition into consideration, it is mostly concerned with what the property should sell for on the open market. It is an analysis based on the house itself, plus the neighborhood, recent sales, demand and other factors that impact value.

There are all kinds of appraisals. For example, in a "drive-by" appraisal, the appraiser simply makes sure the house is standing where it's supposed to be.

Then there's a broker's price opinion, or BPO, in which a real estate professional offers his or her educated guess as to the property's value. And there's a competitive market analysis (CMA), which an agent will use to help a buyer make a reasonable offer or help a seller set a reasonable asking price.

If you are paying $300 or more for an appraisal, make sure you are getting the real thing, which is a formal opinion of market value by a licensed or certified independent appraiser. After all, you, too, want to make sure that the house you want to buy is worth what you are willing to pay for it.

That's not to say drive-bys and BPOs don't have their place in the greater scheme of things. They do. A drive-by may be all the lender requires when housing prices are rising rapidly, and informal BPOs may be all the lender wants when the property is involved in a distress sale.

There are all kinds of ways to choose a real estate agent to sell your house. You may use your brother-in-law, for example, or take a recommendation from a co-worker. But according to an informal survey of agents from across the country, there are plenty of things you shouldn't consider.

The aforementioned relative is one. "I'm sorry, but you just can't mix business and family," said Liane Jamason of Smith & Associates Real Estate in Tampa, Fla.

Don't go with an agent just because he or she has the most listings or the most signs up in the neighborhood, say some of the realty pros. Those agents are probably overextended. If they have lots of listings, said Karen Netterstrom-Dooley of RE/MAX Elite in Melbourne, Fla., "they are not going to give you much attention."

Somewhat surprisingly, the agents who answered the question, "What one attribute would you look for if you were hiring an agent to sell your house?" tend not to think too much of professional designations, the agent's brand or whether he is part of a team.

While the letters behind a name signal a certain degree of professionalism and extra education, many agents said they meant little. "Designations mean nothing to me. I have worked with agents who have their walls lined with them and they are lost," said Kenneth Nance of Only Way Realty in North Myrtle Beach, S.C.

Some respondents believe being affiliated with a large, well-known brokerage is an advantage. But Bev Hourlier of HC Realty Services in San Diego said it doesn't guarantee the agent is any better qualified or trained than an agent from a smaller firm.

Respondents had plenty of comments about the attributes that indicate a standout agent. Here are the ones that seemed to rise to the top:

-- Fit. Agents used all kids of terms to indicate how you "click" with an agent, including philosophy, presence, personality, integrity and trust.

"Chemistry," said Allan Glass of ASG Real Estate in Los Angeles. "Clients who don't establish a personal connection with their agent or broker will put themselves at a disadvantage."

Emily Morrison Griffin of John L. Scott Real Estate in Seattle agreed. "There has to be that special spark that makes you and your Realtor a great team."

"All other characteristics are secondary ... to the ability to trust your agent," said Lou Sansevero of the RE/MAX Alliance Group in Sarasota, Fla.

-- Referrals. Referrals are "golden," advised Joshua Hanoud of Tropic Shores Realty in Spring Hill, Fla. Without them, "you don't know you've gotten a bad apple until you are too far into the process to make a change easily," he said. "As a result, going into the game with someone who has a strong recommendation from a friend or relative can make a huge difference."

Beware, though, warned Paul Howard of NJHomeBuyer.com Realty in Cherry Hill, N.J. "Recommendations are based on the outcome of a particular transaction that may have been uneventful and may have little relevance to a future transaction that may have obstacles the agent has to help the consumer navigate."

-- References. Cindy Greenwald of Prudential California Realty in La Jolla wants to see the agent's current list -- not more than 90 days old -- of clients. Brenda Cunningham of West USA Realty in Mesa, Ariz., looks for someone who has used the agent for more than one transaction. Kimberly Tapscott of Keller Williams Prestige Properties in Stamford, Conn., said the agent should bring the names of at least three past clients that you can call on the spot.

-- Experience. There's nothing like a proven track record, said Sandra Geary of RE/MAX Pros in Rohnert Park, Calif. "While experience is no guarantee of skill, real estate, like many other professions, is mostly learned on the job," said Rae Catanese of Prudential Tropical Realty in Tampa.

-- Sales volume. Isabel Williams of Keller Williams Luxury Homes in Jupiter, Fla., said it's better to work with an agent who's closing 40 deals a year than the industry average of four.

Kirstin Willingham of Bergman Beach Properties in Marina del Rey, Calif., pointed out that recent sales volume is most important because today's market is far different from just a few months ago. And Harold Huggins of Harold H. Huggins Realty in Burtonsville, Md., suggested looking at sales similar to yours.

-- Other statistics. A key ratio for Robert Kelly of RE/MAX Main St. Realty in Moorestown, N.J., is the selling price of recent transactions in comparison to the listing price. An agent who is getting 95-plus percent of the asking price is doing a great job, he says.

Another important number is average days on the market. "An agent whose days-on-market average is 35 or less also is doing a great job," Kelly says.

It's not a good sign if the agent does not provide these key statistics at the first interview, according to Jamason, the Tampa agent. If they don't know their list-to-sale ratio, it's an even worse sign, she said.

-- Technology. Because nearly eight out of 10 buyers start their home searches online, today's marketing is more than just sticking a sign in the front yard. Technology is essential for word-of-mouth advertising and viral media campaigns, said Florida agent Catanese. Can your agent prepare a YouTube video? Can he or she respond in an instant?

Check the agent's online presence, advised Ines Hegedus-Garcia of Majestic Properties in Miami. An agent who knows how to market himself should also be able to market properties, she said.

"The agent who walks into my home should at the very least have a tablet and know how to use it, and show me examples of his listings' social media footprints," said Tapscott in Connecticut.

-- Photography. Pictures are "the language of real estate, yet most agents' look like they were taking pictures while drunk with a cellphone," said Hanoud in Florida. "The level of detail needed for good photography is usually indicative of an agent's attention to detail throughout the process."

Ken Pozek of Keller Williams Realty in Novi, Mich., said good photos can result in a 15 percent to 20 percent increase in showings.

-- Listening skills. "I want (agents) to answer my questions clearly and be able to explain the process of buying and selling," said Teri Andrews-Murch of Lyon Real Estate in Auburn Calif.

Asked Barry Sulpor of Shorewood Realtors in Manhattan Beach, Calif.: "Do you get a strong feeling that this is an agent who will listen to your needs?"

So listen up and follow the advice of these experts to find an agent who's just right for you.