The common wisdom is that would-be homebuyers on the lower end of the credit spectrum will benefit the most from improving their credit scores -- those all-important snapshots in time of how people use their credit.

But that’s not the case, according to number-crunching company CreditXpert, which claims that most people who apply for a mortgage can raise their scores by 20 points -- and do so within 30 days.

Most lenders accept credit scores as static figures. They're not, though -- they are dynamic, says Mike Darne, vice president of marketing at CreditXpert. Lenders should look at every applicant’s score "not for what it is," he says, "but for what it could be."

So should borrowers, for that matter.

CreditXpert found that 65% of a representative sample of people who bought homes in the last six months, or who intended to buy in the next six, were never given the opportunity to improve their credit scores. Out of those who were given the chance, 7 out of 10 took steps to do so, and the main reason was to save money.

How much money you can save varies, of course. But in one example, a woman raised her score by 40 points, earning her a lower rate from her lender and trimming her principal-and-interest payment by $158 a month. She also saved $131 on mortgage insurance, for a total of $289 a month.

Just for taking rudimentary steps to raise her credit score, she'll save tens of thousands of dollars over the 30-year term of her $400,000 mortgage.

Credit is just one of the three C's lenders look at when deciding whether to provide financing to someone. The other two are capacity, or your ability to repay the loan, and collateral, which is the value of the property you're buying.

But credit, Darne points out, is the only one over which you have any control. You can’t very well boost your income instantaneously, and you certainly can’t raise the value of the house you are buying. But you can raise your credit score -- sometimes enough to make a real difference.

To do so, there are numerous steps you can take. First, go over your credit report to search for errors and have them expunged. Credit reports are often riddled with mistakes, such as accounts that don’t belong to you or paid-off loans that are described as still active -- or worse, as delinquent.

Another step: Don’t utilize more than 35% of your maximum credit allocation. For example, if you could max out all your credit cards to a total of $10,000, keep your combined balances below $3,500. That will show that you know how to handle credit. And always be on time with your payments, of course.

Some actions in the world of credit scores seem counterintuitive or contradictory. For instance: In general, you shouldn't apply for any credit that you don't need. But in some cases, it may help your score to take out a new credit card. Likewise, paying off your balances and debts is a good thing -- most of the time. Paying off an old debt could actually be detrimental because the action will render it a "new" item on your report, which will be counted against you. So it may be better to just leave it alone.

These steps can be tough to navigate, and may not even be helpful in the short term. But CreditXpert is testing a credit optimization tool that anyone can use to determine what (if anything) they can do to boost their credit score and lower their mortgage costs.

After answering a few questions about the anticipated purchase price and loan amount, the system will check your credit file and use predictive analytics to identify what you might do to meaningfully bump your score. Then, it will send you to a lender who can use the tool to produce a step-by-step plan to help you reach your potential.

Optimizing your credit won’t come without a cost. But in the long run, your savings could be substantial.

In the example above, the woman who raised her score by 40 points would have to spend $2,810 -- maybe through paying off a credit card or two, or paying down other accounts -- to take her score from 640 to 680. But her monthly payment would be $289 lower, so in just 10 months, she would recoup her out-of-pocket costs.

By the way, credit optimization should not be confused with credit counseling or credit repair. Whereas optimization leverages sophisticated data science and predictive analytics to look for short-term opportunities, credit counseling is usually a longer-term process. Those interested should seek out face-to-face counseling platforms run by legitimate organizations.

"Credit repair" is another story altogether. Buyer beware: The Federal Trade Commission has brought numerous actions against so-called credit repair services, and has partnered with some states to bring hundreds of additional lawsuits. Many of these charlatans take your money but do little, if anything, to help with your credit.

Attaching a check to the offer on a house you hope to purchase is the right way to signal your intentions to the seller. The larger the check, the more serious the buyer.

But putting up earnest money is not without risk. If you don’t abide by the contract you and the seller sign, you could end up forfeiting the entire amount.

Margaret Goss, an agent in Winnetka, Illinois, has had only one client lose their earnest money, but it was a doozy. Goss commented -- on an ActiveRain article on the topic, written by Massachusetts agent Bill Gassett of RE/MAX Executive Realty -- that when closing day came for this client, they backed out. The reason? “The market was changing and they felt they had paid too much," said Goss. "They lost a bundle.”

More on that in a moment. First, some basics.

Earnest money isn’t the same as a down payment. A down payment is the amount lenders require borrowers to put into the transactions up-front so that the bank can feel secure in financing the balance of the home’s cost. In other words, if you bring, say, 10% of the purchase price to the closing table, the lender will hand over the other 90%.

In contrast, earnest money is a sign of good faith to the seller. It tells the seller you intend to move forward. It can range from as little as $500 in some markets to several thousand in others, and usually increases when competition for houses is strong.

Your earnest money can be rolled into the down payment when you sit down at closing -- but it also can be lost if you fail to reach that point. You have to follow the letter of the contract. And timing is everything -- especially when it comes to any contingencies written into the document.

Contingency clauses protect both buyer and seller. But the more contingencies, the greater the possibility of the deal falling through. So in competitive markets where houses are flying off the proverbial shelves, some buyers are forgoing home inspections and other protections in order to present sellers as clean a deal as possible.

It always behooves buyers to protect themselves against unforeseen circumstances, but contingencies can cause trouble if you run out of time. Most real estate contracts include timelines that must be adhered to by both buyer and seller.

Take the home inspection clause, for example. Usually, the number of days you have to order the inspection and receive a complete report of the findings is agreed to by both parties and written into the contract.

If the inspector finds defects you don’t want to deal with, you can back out of the purchase and your earnest money will be returned. Here, advises Gassett in his ActiveRain post, you should notify the seller that you want out, in writing, prior to the expiration of the inspection contingency.

If you miss the deadline, either because the inspection wasn’t completed in time or because you failed to notify the seller that you are no longer interested, the seller can keep your deposit.

The same holds true for the mortgage contingency. Cash buyers don’t have to worry about this, but most people need financing, so they write into the contract how many days they have to secure a loan. Sometimes, a maximum interest rate is also specified.

That’s one reason smart buyers get themselves preapproved by a lender -- not just prequalified, but preapproved for a loan up to a certain amount. Then, when they find a place they want, they can move quickly. But again, if you miss the deadline -- or fail to tell the seller in writing that you are unable to secure a loan -- you can lose your deposit.

The seller can grant a mortgage extension if you want to keep hunting for a lender, but Gassett suggests getting that permission in writing.

Another contingency to keep in mind involves the appraisal. This protection allows you to walk away if the selling price turns out to be more than what the appraiser says the property is worth. Like the others, this contingency comes with a timeline.

If, during the post-contract, pre-closing period, you simply change your mind about the house, you can sometimes use one of the above contingencies to back out of the deal. If the seller is holding backup contracts just in case your deal falls through, or if other buyers are knocking on their door, they will probably let you skate.

But if you can’t demonstrate a good reason for changing your mind, they could hang on to your earnest money. After all, they've probably taken the house off the market and missed showing the place to other interested parties.

Now the lawyers become involved, and that could tie up your money for months -- money that you might need to put up for another house. So read your contract closely and follow it carefully.

One last word on earnest money, which also applies to deposits on new-build homes: Make certain the money is held in a dedicated escrow account. Some financially strapped homebuilders have mingled customers' deposits with their own operating funds -- and when the businesses went under, the money was gone.

It’s not an everyday occurrence. But once in a while, a homebuilder abruptly shuts down, leaving customers holding the proverbial bag.

At the height of the Great Recession, for example, dozens of homebuilders suffered adverse changes that affected their buyers, whether that meant the company went bankrupt or was purchased outright by another entity.

More recently, a major Florida builder called Metro Home Builders Inc. filed for bankruptcy this summer. When it closed its doors, it left some 60 houses in various stages of construction. In one case, according to the Naples Daily News, the company was paid over 75% of the home’s contract price but left it “not even half built.”

And in Raleigh, North Carolina, a local TV station reported that eight families have been left with “a mountain of debt” -- and no homes -- when J&R Homes suddenly went out of business.

Stories like this should send shivers down the spines of every homebuyer, and they should take every precaution to protect themselves. Buying (or building) a house is a participatory sport; you can’t just sit on the bench if you want the process to be successful.

If your builder shuts down before your house is completed, the best advice is to lawyer up right away. Do not hesitate. As soon as you get wind of any financial difficulty, gather up all your paperwork and run, don't walk, to an attorney. And not just any attorney, but one who specializes in real estate law.

Bring the lawyer your signed contracts, along with photocopies of every check you've written to the builder (and to any affiliates) that has been cashed. You’ll also want to stop payment on any outstanding checks that have yet to clear.

At this point, the likelihood of saving your investment isn’t good, especially if the builder is insolvent or declares bankruptcy. Secured creditors with the right to foreclose are paid off before the builder's buyers. But those who are first in line with their claims stand the best chance of getting at least some of their money back.

Some advice for anyone thinking about entering into a contract with a homebuilder: Thoroughly check out the company before you sign on the dotted line.

Start by looking at the firm’s financials, either with its local bank and lenders or by running a credit check. Make sure it is on sound financial footing and is unlikely to go belly-up in the middle of construction. Ask to speak with the company's backers -- if the builder balks, your antennae should wiggle.

Next, walk the construction site and start a casual conversation with the subcontractors. Speak with their foremen to make sure everyone is being paid -- on time and in the proper amounts. If they are being shortchanged or stiffed, they’re likely to let you know.

If the subs aren’t happy, the builder is likely to be in some kind of financial squeeze, usually from lenders and subs on another project. According to one attorney, it's very common for builders to find themselves in trouble when they start using funds from one property to pay vendors for work elsewhere.

Also, check out the builder with your local Better Business Bureau and consumer affairs agencies. Too many complaints about missed deadlines or unfinished work could be another sign of trouble.

Once you are satisfied the company is in sound financial shape, proceed cautiously. Make sure the contract commands the builder to put all the money you pay during construction in escrow, and not to mingle it with the company's operating funds. That way, your money will be safe until closing, when it will be handed over to the builder. And add a clause that says if the company declares bankruptcy, your contract is void and your money will be returned.

Prior to construction, make sure all the necessary permits have been issued and the required bonds have been posted. During construction, make sure the subcontractors are being paid by obtaining copies of all lien release forms, which they should sign every time they are paid. Otherwise, they can file a lien on your house, and you may not be able to close on the place until the liens are settled.

If the builder bails before your place is finished, you may be able to make a claim against the builder’s insurance or security bond. You also may be able to enforce the warranty the builder provided to protect you against defective craftsmanship and structural issues.

Some states have guaranty funds, to which aggrieved buyers can file claims for unfinished work. But the investigations often take months, and payouts are slow. According to one press report, 97 claims were filed with the Maryland Home Builder Guaranty Fund between July 2017 and June 2018 -- but there was only one payout.

Finally, let’s discuss what happens if you move into the new house, but your builder fails before taking care of all the “punch list” items -- either cosmetic or structural -- that were noted on your final walk-through before closing. They promised to fix those things, but now they're out of business.

Here, there’s little you can do other than make a claim against the warranty you were provided. If you haven't yet closed, you might demand that some money be set aside in escrow to cover the cost of said issues. That way, if the builder goes kaput, the money for any repairs will go to you, allowing you to fix things on your own.