Reprogram your thermostat settings for winter. This includes setting the clock to standard time. If your thermostat uses batteries it may be time to replace them.
Clean or change the air filters.
Keep doors and windows closed. This will reduce the heating load.
Make sure your vents and grilles are unobstructed.
Avoid excess use of exhaust fans.
Open window shades and awnings to increase direct sunlight and lower the heating load.
Make sure no heat-generating appliances are near your thermostat.