1. Cover Fireplace - If you do not use your fireplace you need to close the damper and install a removable panel. If you do in fact use your fireplace, installing an air-tight glass doors over working fireplaces
2. Insulate Drop-Down Stairs - This is the attic entry. You can either do it yourself using polystyrene insulation and construction adhesive or you can purchase a polystyrene hood that will fit over the drop down.
3. Patrol for Heat Leaks- This will be perfect to do on a bright Saturday morning. Spend the day looking around the house for gaps in doors, crawlspaces, attic. If you find daylight creeping in, seal it up!
4. Deal with Air Conditioners- If you have a window air conditioner, remove it during the winter season. If you have a through the wall conditioner place an insulated cover on it.
5. Fine Tune Boilers and Furnaces- If you have a gas furnace, you should consider scheduling a tune up. This should be done yearly.
6. Improve Windows- Take a look at your windows and feel how well they are insulated. If you feel a lot of coolness coming from the window you can do whatever your budget will allow. Whether that be completely replacing them or adding weatherstripping or a storm glass.
7. Add or replace weatherstripping around doors.
(Source: Popular Mechanics)