The first step is to get some loose-fill insulation blown into your attic. This is the easiest and least expensive initial option. There are two choices: cellulose or fiberglass, with a slight quality advantage going to the fiberglass, according to the trades people I speak to. Insulation performance is measured with something called R-value. Be sure to specify that enough insulation be blown in to bring your attic up to R-40. This should cost about $700 to $1000 for a 1000 sq. ft attic.
You may also be able to have the same kind of insulation blown into the walls, but only if they’re completely hollow. Unfortunately, that’s not very common, even in poorly insulated homes. Adding rigid foam to the outside or inside face of exterior walls (underneath new siding or drywall) is really the only practical option.
For financial help, check out a Federal government program called the EnerGuide for Houses Grant . It provides money for renovations that make your home easier to heat. The amount you get back is based on the reduction in energy consumption based on assessments before and after the work gets done.