Adjust your thermostat. The bigger the temperature difference between outside and inside your home, the harder your home works to keep cool, which can result in spiked energy usage. Try to adjust the temperature 3-4 degrees warmer than you normally would.
Use ceiling or floor fans to keep cool. Fans offer an inexpensive alternative to setting the thermostat to a lower temperature. Remember, fans cool people, not rooms, so turn them off when you leave the room.