Keep your cool.
If you're using a window or room air conditioning unit, make sure that the unit itself is properly insulated. If you are working or relaxing in one spot, close all doors and openings to other rooms in your home. This will keep your space cool and comfortable while avoiding the loss of treated air to unoccupied spaces in your home.
Central air conditioning vents aren't always in the most convenient places. Make sure to check that no furniture is obstructing them - otherwise, you could be paying to cool the bottom or back side of your sofa instead of your living space! There are also plastic pieces, available at hardware stores, that fit onto vents in order to direct air in a more useful direction.
Close off certain vents.
Close off vents in unoccupied spaces in your home to help direct treated air to where you need it most. Pay special attention to basement rooms and lower levels, where cool air naturally settles. Closing vents in these spaces can increase comfort in other rooms that may cool less easily.
Try 78 degrees.
Seventy-eight degrees is described by ENERGY STAR as the optimal temperature setting for maximum efficiency, comfort, and energy savings. You might be surpised by how cool 78 degrees feels inside your home, where your air conditioner also regulates humidity. Pairing this temperature setting with the use of a ceiling fan in occupied rooms will help keep you comfortable without breaking the bank.
Maintain your A/C.
When it comes to your cooling equipment, a little TLC can go a long way. If you haven't yet changed your central air conditioner's filter this season, now is the time to do so. Take a few minutes to change it once every 3 months during times of heavy use. Also check external parts of window air conditioners and/or your central air conditioner's outdoor condenser unit and remove debris from plants and other obstructions.