Use compact fluorescent light bulbs.
Compact fluorescent bulbs use 75 percent less energy than incandescent bulbs and last up to 10 times longer, according to Energy Star. They're more expensive than traditional light bulbs, but it only takes about three months to make up for the higher sticker price in energy savings. For the most impact, replace the bulbs in the fixtures you use most, such as the kitchen, bathroom, dining and family room lights.
You will save $85 over the life of the bulb for each 60-watt light bulb you replace with a 15-watt compact fluorescent, according to Energy Star. You'll also save 543 kilowatt hours of electricity and reduce your CO2 emissions by 833 pounds.