First of all, make certain your windows are well insulated. It may be a good idea to pick up some weather stripping or caulk to seal any cracks around the windows.
Next, install ceiling fans in multiple rooms of your home wherever possible. You can reduce the cost of energy by using ceiling fans instead of an air conditioner on days that are not as hot. In the evenings, open the windows to allow the ceiling fan to circulate breezes throughout your home.
Make certain your air conditioner is clean. Mark your calendar to check filters to see if they need cleaned or replaced on a monthly basis. On exits, make certain there is no debris, plants or shrubs too close to the unit. It is also a good idea to clean the air conditioning unit thoroughly at the begin and the end of summer. This can be done by simply removing the cover and spraying the unit with a water house.
Check your attic to see if there are roof vents for the hot air to escape. Some older homes were built without these vents, which can cause the heat to be captured in your home. You might also consider adding attic fans or fans in rooms with a lot of heat to pull the hot air out of the home.
Avoid using heat producting appliances during the day. If you use an electric or gas dryer to launder your clothes or if you do a lot of baking, try doing this as late in the evening as possible. This will keep the home cooler during the day.
And finally, if your home is in an area lacking shade, keep blinds closed. You may also consider purchasing awnings or even planting a tree to add more shade to the sunny side of your home.