3. Install weatherstripping
Weatherstripping is any product that seals air leaks at joints where two surfaces meet and move, and it’s ideal for the budding do-it-yourselfer. All you need is a utility knife, tape measure and cleaning tools. Apply self-adhesive strips of felt, foam, rubber or V-strips, which fold into a V and double up when closed. More experienced DIYers can try compression weatherstripping, rigid foam or foil tape.