Set your thermostat at as high a temperature as comfortably possible in the summer, and ensure humidity control if needed. The smaller the difference between the indoor and outdoor temperatures, the lower your overall cooling bill will be.
Avoid setting your thermostat at a colder setting than normal when you turn on your air conditioner. It will not cool your home any faster and could result in excessive cooling and, therefore, unnecessary expense.
Consider using an interior fan along with your window air conditioner to spread the cooled air through your home without greatly increasing your power use.
Avoid placing appliances that give off heat such as lamps or TVs near a thermostat.