1. Weatherstripping and caulking. The first step in getting the most out of your current windows and doors is to plug any air leaks. Caulk inside and outside your window casing and use weatherstripping in the sash.
2. Heavier curtains. Like pulling on a nice, cozy sweater when you get chilly, switching out lighter summer curtains for heavier drapes in the winter is a smart idea. Decorating-wise, it looks more appropriate during the cool months to have something lush and rich, like velvet or heavy linen, on the windows, and the fabric provides extra insulation and blocks drafts.
3. Doorway curtains. In an entry with a glass door, try hanging a floor-length velvet curtain directly behind the door — pulled to the side during the day, it would be a dramatic decorative accent, and at night, when pulled shut, it would provide an extra layer of warmth between the glass and the great outdoors.
5. Layered window treatments. To dress your windows really warmly, bundle them up in insulating shades (or cellular shades) with curtains hung on top. This elegant look makes any room feel more finished and will keep your house warmer.
6. Draft-stopping door snake. This may seem a little old timey, but there is nothing like a door snake for quickly and easily stopping a big draft from whooshing under your door. Thankfully there are many stylish door snakes being made now (like the one shown here); a quick search on Etsy is sure to produce tons of cute options.
7. Insulating window film. This product sticks directly to your windows, providing an extra layer of protection from the elements. Be aware that your windows won't be perfectly clear with window film applied — which is probably fine for windows in some parts of the house, but you may not want to use it everywhere if the look bothers you.
8. Storm windows and doors. These are costlier than some of the other items on this list but could make the most difference. According to the Environmental Protection Agency, adding a storm window to an older window that has been weatherstripped provides the same or better energy savings as a new dual-pane window.