Any serious baker can back up this fact: Don't open the oven door when cooking at home. When you get your oven preheated to the temperature you need, place whatever you're roasting or baking inside, and leave the door closed. When you open and close the oven to check on your food, it cools the inside by about 25 degrees each time. That not only wastes energy, it increases the overall cooking time and can change the outcome of whatever it is you're cooking. Just flip on the light switch and peek through the window to check on your food.

When it's cold outside, there are easy ways to fully maximize the efficiency of your home's heating system. One of the best things you can do is to raise the temperature on your thermostat slowly, allowing it reach the desired temperature one or two degrees at a time. If you raise the heat quickly, your pump uses something called a heat strip, which is a huge energy waster. And while small space heaters are convenient, don't rely on them to heat rooms on a regular basis. They use as much as 1,500 watts of energy, which can add up to serious dollars on your utility bill over time.

It takes about five years of driving a hybrid for the savings to catch up to the extra cost of the fuel-efficient car. One quick way to start seeing real savings really fast is to buy a used hybrid. With over 2 million hybrid cars sold in the United States annually, car dealerships are flush with lightly used hybrids that are marked way below their sticker price. Make sure you buy a used hybrid that comes with a warranty; many dealers offer up to 7-year/100,000-mile warranties. But if you see a used hybrid with more than 100,000 miles on it, consider avoiding it, since it can be expensive to replace the battery.