Close your crawlspace vents during the winter to prevent pipes from freezing and cold air flow under your floor.
Have your HVAC system tuned up and check monthly to see if the filter needs replaced.
Remember to turn the thermostat up or down when you leave (maybe check into a programmable or smart thermostat).
When you need to adjust the thermostat with an electric heat pump (in the winter), do it only 1 or 2 degrees at a time (this gives the unit a chance to catch up with your needs and prevents the heat strips from coming on and using more electricity).
Inspect your HVAC duct work for leaks or insulation damage.
Check to see how much attic insulation you have (a general rule of thumb is if you can see the tops of your ceiling framing, then you don't have enough insulation).
Check to see if your attic stairway, access panel, or doorway is insulated and weather stripped.
In the winter, reverse the motor direction to run clockwise on your ceiling fans to circulate the warm air at the top of the rooms.
Caulk or weatherstrip any gaps around window trim, door trim, or any other obvious areas.
Add storm doors or storm windows around doors or windows that may not be energy efficient.
Insulate hot water pipes and possibly your hot water heater to prevent heat loss from colder temperatures.
Set your water heater temperatures at a maximum of 120* F or check into installing a timer (an electric water heater can be the largest user of electricity in a house).