Avoid Heat Producers
Do not use appliances that produce a lot of heat during the hottest part of the day.  This includes things like dryers, ovens and stoves.  Running these appliances at the same time as your AC will just make it work harder and consume more energy.

Freezer Placement
Although your freezer keeps things cold, it actually generates a lot of heat.  You can avoid excessive heat in your main living areas by moving your freestanding freezer to the basement or garage during the warm summer months.  This will help reduce the load on your AC unit.

Blower Test Your Doors
Blower door testing is offered by many utility companies.  The blower door depressurizes your home and shows you any air leaks that your home may have.  Your local utility company will be able to let you know whether they offer this service to their customers.

Seal Leaks
Once you have located leaks you will want to seal them using caulking, weather-stripping, and insulation.  A well sealed home can save as much as twenty percent on energy costs.