Doors are much easier to seal than windows as they have fewer moving parts. To add weather stripping so it doesn't cause binding, it is best to even out the gaps around your door before starting. If possible, shim the door hinges to create a uniform gap all the way around your door.
The weatherstripping you should use is the same used for windows. Plastic V-strips and spring bronze are great for the top and sides of the door. You must use a different material for the bottom as you deal with heavy foot traffic. There are special seals designed for door bottoms including door sweeps, door shoes and thresholds.
