To save money and improve your home's energy efficiency, you'll want to start with its outer shell - the walls, windows and doors - then move to the inside spaces.
If you're not sure what to do, contact your insurance company and ask if they have consultants who can assess your home and make recommendations.
Old homes with big attics are notorious for leaking air due to inconsistent or thin insulation. If you hire a contractor, make sure they use an infrared camera during and after installing fiberglass, cellulose and most foam insulation, so they can see any voids or gaps.
Replacing single-glazed windows will give you one of the biggest bangs for the buck, because ENERGY STAR-rated replacement windows are typically $15 more than other windows, and can result in a savings of about 12% in heating and cooling bills.
The age of your furnace may determine what you should do about it:
An annual HVAC tune-up can help your system work more efficiently. You can also install a programmable thermostat and check to make sure all ducts are property sealed.
The lighting cost of a CFL is less than one-third that of incandescents.