Tighten things up Make sure your ductwork is sealed and the home has appropriate insulation. The tighter the seal, the less energy needed to lower the temperature.
Keep cool air inside and hot air outside Crack your windows at night to let the cool air in, but button them up during the day to keep the heat out. Close window blinds to prevent the sun from heating your home (especially on the western side–most solar heat gain comes from that direction when the sun is near the horizon).
Consider getting a whole-house fan In the evening, run this ventilation system to exhaust air out of the house at night to cool the building. In the morning, close it up. It’s less expensive than an air-conditioning system. I recommend AirScape fans.