First thing first, make sure that the air conditioner is not exposed to direct sunlight. 

As it has been observed that a shaded air conditioner consumes 5 % less electricity 

as compared to those exposed to sunlight.

While switching on the thermostat, set it at 78°F for each degree lower would 

mean 8% increase in the energy consumption. 

Switching your thermostat to a colder setting the moment you turn on the air conditioner 

will only increase your power consumption. For cooling, 24°C is the best temperature