A well-insulated home with blinds lowered and curtains closed will do the trick. Keep blinds and curtains drawn against the bright summer sun. Plant deciduous trees on the south and west sides of your house. They'll keep your home cool and you'll save on air conditioning costs. Instead of an air conditioner, a few fans in the right places will keep things cool.
Fans cost less than air conditioning and use less energy.
Window air conditioners will work better if installed away from direct sunlight. If you must use your air conditioner, clean coils and compressor compartments regularly. Fix your tea or instant soup with water boiled in the microwave. It saves time and energy. Glass and ceramic cookware decrease cooking temperatures by an average 15 degrees Celsius.