Clean Out Your AC
You can save lots of energy just by keeping your air conditioning unit clean.  It is a good idea to inspect the entire outside the unit for dirt and dust when you replace the filter each month.  A clean air conditioning unit is a more efficient air conditioning unit. 

Clean Your Coils
You can also save money by keeping the condenser coils of your refrigerator clean.  You can find these coils at the back of your refrigerator.  Dusty coils mean that your refrigerator will work harder and use more energy. 

Add a Ceiling Fan
You can reduce both heating and cooling costs will a well placed ceiling fan.  When placed in a stairwell they can push warm air down during the winter months and cool air up in the summertime. 

Unplug Appliances When they are Not in Use
Even when they are turned off many appliances continue to use energy.  Examples of such appliances include microwaves, VCRs, and coffee makers.  Any appliance that has a timer or clock will continue to draw power even when it is off.  A convenient solution is to place these types of appliances on a power strip that can be simply switched off instead of unplugging them all the time.