Various factors drive operating costs for your heating and cooling system. The local climate, your area's electric (or gas) rates, even how often doors and windows are opened and shut affect the costs to run your heating & cooling system. Know the factors, so you can save money on electric bills and maintenance.
Of course, there are some factors you cannot control, like climate. For example, a central air conditioner will run a lot harder and get more use in Florida, than in the Northeast. But you can lower operating costs by better insulating your home, and by keeping windows and doors to the outside shut as much as possible. Also, look at household additions, such as ceiling fans that can better distribute heated or cooled air throughout your home.