7. Turn Off The Lights Whenever You Leave a Room
Or, in rooms where kids come and go a lot, install vacancy-sensor switches (about $20 each). Don't worry about the surge of energy consumed when you turn a fluorescent bulb back on; as long as the light remains off for at least 5 seconds, you come out ahead. And if you swap in an LED instead (see No. 5), there'll be no extra consumption or early wear and tear from turning the bulb off and on.
The payoff: You could save nearly $100 on your annual electricity bill.