Safety First—Be sure that you have working smoke detectors and at least one carbon monoxide detector. Check the batteries and be sure that you have at least one smoke detector near all of the sleeping areas and at least one on each floor of the house. Battery operated smoke detectors are inexpensive and easy to install. Another good idea is to have 110v electric (with battery back-up) smoke detectors installed on each floor, and have them wired together so that if one goes off, they all sound the alert. The benefit of this is that if there is a fire in the basement while you are sleeping, the upstairs detector will alarm because it is hard-wired to the detecting detector.
If you have a gas furnace or any gas appliances, there is always the possibility of carbon monoxide poisoning should any of them ever malfunction. Carbon monoxide detectors have a battery backup and can be purchased from most hardware stores and home centers. They are inexpensive and easy to install, usually can be plugged into a common 110v receptacle.
Invest in a programmable thermostat or thermostats. Programmable thermostats are digital and typically very accurate. They allow for easy programming of temperatures for different times of the day, including nighttime and workday setbacks to save energy.
Change your furnace filters and use filters that will actually filter out particles smaller than a mouse! The typical furnace filter is simply designed to keep objects from getting into the mechanical parts, namely the blower fan. Find out the size of your filter(s) and replace it with a high-grade furnace filter that will stop air pollutants, allergens and dust from circulating within your home.
Check the insulation and add if necessary. Also, check your weatherstripping and add or replace as necessary. Your electric or gas company may have someone who will come out to your home and do an energy audit free of charge.
Also, if you have a fireplace and/or woodstove, make sure that it is clean and operating correctly. If you're not sure what to look for or how to do any cleaning or repairs, check with a qualified, licensed fireplace shop or chimney sweep.
With the higher costs of energy, it's important to do whatever you can to create and maintain an energy-efficient home. Fall is the ideal time for weatherization projects, so create a warmer home and save yourself some money at the same time.