Using ceiling fans to circulate the air throughout the home. Therefore one can avoid turning or using the A/C for as long as possible. This is also a great technique on those cool summer nights when the windows can also be left open.
If the A/C unit is experiencing multiple breakdowns, or is becoming too costly to maintain it may be time to consider replacing it altogether. This can drastically help decrease the utility bills during the summer months.
Cool air (warm air in the winter) can escape easily in a home through the gaps between the walls. Filling in these gaps with insulation can help prevent too much of the cool/warm air from escaping.
In addition to powering off and unplugging appliances, turning off the lights after exiting a room can also help reduce utility bills. Using only natural light during the day and maybe setting the mood at night with candles are additional tips.
Keeping up with at least a once a year maintenance can help the A/C run as efficiently as possible and guarantee that the unit itself is leak-free. Clean air filters are also very important in regards to unit effectiveness.
Consider installing a programmable thermostat so the unit is not constantly running. This way the A/C unit is set automatically to a higher temperature when not home.
After refrigerators the clothes dryer usually takes up the most energy in the home. Taking advantage of the blazing summer sun and hang the clothes out to air dry.
If the home is under shade it will help keep the house cooler without using excess energy. Consider planting some trees for the long-term savings the shade can provide.
Take advantage of the summer haze and turn to barbeques and grilling meals outside. It will help reduce the use of the A/C unit to cool down the home.