Consider, where practical, reducing number of lighting fixtures or lamp wattage because for every four watts of illumination reduced, one watt of air conditioning need is reduced. Caulk any cracks around window and door trim. Make sure refrigerator door gaskets seal properly. Keep refrigerator coils clean. Vacuum at least twice per year.
Compact fluorescents are some of the most efficient replacements for incandescent bulbs.
They give a comparable amount of light for one-forth the energy.