8 Caulk your windows. Cut drafts around minute window cracks. Use an interior formula caulking indoors and an exterior formula outdoors for best results.
9 Shrink-wrap the windows with a dedicated plastic film from the hardware store. It's fast, cheap and adds an insulating thermal layer that can reduce heat loss through the window by 25 to 50%!
10 ... Or replace them altogether. Older windows can be upgraded with EnergyStar-rated windows that will reduce heat loss in winter (and heat gain in summer).
11 Turn on your ceiling fans. Reverse them from the summer setting, and you'll push warm air back down from ceiling level into your living area. Fans use less energy than the furnace.
12 Vacuum the coils at the back of your fridge. Consider this seasonal maintenance. The coils disperse heat taken from inside the fridge and when they're covered in a layer of dust, they disperse the heat less efficiently, meaning your fridge uses more energy to keep its cool. And that's not cool.
13 Switch to heavier drapes. Velvet drapes will cut drafts, and a change of window treatment always provides a nice transition between seasons anyway. Be sure to keep the drapes of south and west-facing windows pulled back on sunny days, so your home can absorb plenty of ambient heat.
14 Wrap your air ducts and hot-water pipes to reduce heat loss. Use pipe insulation wrap or polyethelyne or neoprene pipe sleeves.
15 Close heat vents in guest rooms, attics, store rooms and other unused spaces. Why divert heat and up your energy consumption for rooms that aren't in use? Close the vents, then close the doors to these rooms. Just don't forget to open the ducts when guests stay over (unless you don't want them staying too long!)
Image courtesy of Pottery Barn.