Many electronic devices such as computers, DVD players, microwaves and cell phone chargers use electricity even when they're just sitting there. Unplugging such items when they're not being used can cut back on electricity costs significantly. A simple way to cut off power to these energy hogs is to plug them into a power strip and turn off the strip when they're not in use.
Taking control of the thermostat is an important step. During summer, set your air conditioner to the high 70s when no one is home. Don't forget to cover the windows during the day, since blocking out sunlight can keep temperatures lower. During winter, set the thermostat to the mid 60s and wear sweaters. When nighttime arrives, drop the setting to 55 or so. Cooler temperatures at night can actually help you sleep better, so it's a double benefit. And check the water heater's thermostat too – it should run somewhere between 120 and 130 degrees.
Changing out all your light bulbs with CFL bulbs can save up to $40 in electricity costs per bulb. CFLs last up to 10 times longer than incandescent bulbs, and because they stay cooler, they can reduce your air conditioner usage as well. Make a habit of turning off the lights when leaving the room, and those savings will go up even further. Better still, install motion-sensitive light switches that turn the light off automatically when the room is empty.