Watch the Watts.
Gadgets such as the Kill-A-Watt and the Watt Minder help you find the biggest energy users in your home. Plug an appliance into one of these devices and it will tell you how much energy it uses per hour, month, or year, and how much it's costing you.
Wattage meters cost about $20 to $30. If you are interested in the bigger picture, rather than monitoring one device at a time, the Power Cost Monitor tracks, in real-time, the electricity use in your entire house and shows how much it is costing you. The monitor costs about $130 and attaches to your electric meter.