Keep your thermostat set at 78 degree Fahrenheit; or higher, and on "auto," not "on." Each degree can mean up to 9% savings on cooling costs.
If your central or room air conditioner is more than 10 years old, it could be doubling your cooling costs.
Use ceiling fans to circulate air. They use about as much electricity as a light bulb and can make you feel comfortable at higher thermostat settings. Oh, and do not forget to turn fans off when you leave the room.
Clean or replace your air conditioner filter monthly so your A/C runs efficiently.
Plan ahead! Schedule heat-producing activities like laundry, ironing, and cooking at cooler times of day when possible.
Turn off lights when not needed, especially incandescent and halogen types.
Be aware of temperatures! If it's cooler inside than outside, then close all windows and drapes. If it's cooler outside, open everything up to ventilate and let the outside air cool your house.
Use drapes, shades, awnings and reflective materials to reduce the heat entering through glass.
Use room exhaust fans in the kitchen, laundry and bathroom to pull hot, humid air up and out.
Apply weather stripping and caulking around all doors and windows to keep the chilled air inside your house.
Install a setback thermostat (Clock thermostat) that automatically switches your air conditioner to a higher cooling setting while you are away.