First, find the source of drafts in your home using a matchstick or candle. Slowly move the flame around the window frame. If the flame bends or flickers at any point, use a small sticky note to mark the spot so you can come back and seal it.

Make or purchase a draft snake to prevent warm air from escaping—or cold air from entering—around the sills of drafty windows and under doors. Draft snakes can be made of virtually any fabric, including old towels or socks.

A good way to keep warm air inside is to install interior storm windows, which fit into the inside of an existing window frame. As an alternative to storm windows, Plexiglass or clear acrylic panels can be secured with screws in the corners of the window frame.

Most home improvement stores sell plastic shrink insulation kits that can be easily installed in minutes. Apply plastic shrink film to the indoor window frame with double-sided tape, then heat the plastic with a blow dryer to shrink the film and remove wrinkles.

Window caulking is one of the first lines of defense against cold air—but it can develop cracks or gaps over the years. Seal small cracks by adding a new layer of caulk or by adding rope caulk, which can be molded into the cracks. If there are large gaps or cracks, remove the old caulk and replace it.

If you don’t need to open a window all winter, use bubble wrap to seal it. You can buy bubble wrap by the roll and cut it to fit your drafty windows. Use double-sided tape to keep the plastic in place.

Seasonally swap out your lightweight curtains for insulating window treatments. Opt for heavy draperies or layered curtains; honeycomb shades, which trap air between layers of fabric to provide insulation; or Roman shades.

Repair, replace, or add weatherstripping around drafty windows and doors. Choose from self-stick rubber weatherstripping, sold in rolls; felt weatherstripping, sold in sheets; V-seal weather stripping, sold in both plastic and spring-metal versions; or expandable spray foam weatherstripping, sold in aerosol cans.

If you want more winter tips, try: 

7 Things to Do Right Now for a Warmer Winter

11 Ways to Winterize Your Home on a Budget

10 Space Heaters We Love