Layering clothes helps prepare you for different conditions and activities. Underwear Provides basic insulation and moves moisture away from skin, preventing chill when activity stops. Insulation Use one or more layers, depending on conditions, including layers of pants to keep your legs warm. Sweaters, sweatshirts, and other similar garments are good insulators. Outer Shell Choose garments that are windproof, and preferably waterproof, such as those made of coated nylon or polyester.
Good fit is crucial.
If the shell is too big, heat loss can occur rapidly. If it is too small, you may not have enough room for insulating layers .