Keep your doors and windows closed when you have the A/C on. Also weatherstrip and caulk your doors and windows to seal in cooled air.
Out with the old, in with the new
Your refrigerator uses the most energy of any appliance in your home if you consider that it runs 24 hours, seven days a week. According to ACEEE, there are 126 million refrigerators and 38 million freezers using 200 billion kWh a year.