Make sure registers for supply and return air are not blocked by draperies or furniture. Clean or replace furnace filters monthly. Unless you have a gas or oil furnace, which needs air for combustion, keep crawl space vents closed in the winter. Closing warm air registers in unused rooms will save you little or no money if you have a central heating system with duct work. Your duct work has been sized and installed to operate most efficiently when warm air is allowed to flow freely throughout the house.
Ceiling fans work well in the winter as well as in the summer.
In winter, reverse the direction of the blades if you can to push warmer air on the ceiling down. If you have window air conditioning units, remove them in the winter to prevent heat loss through the units. If you can't remove the units, buy a cover. INC. is a specialized distributor located in New Richland, MN with the committment to offer product that provide comfort and energy savings to the comsumer. The higher the better.