To accommodate extra layers, your baselayer should be trim or even snug, and your midlayer should fit under your shell without restricting your movement. Don't forget about small details like zippers. If every layer has one, the zipper pile-up around your chin might be unpleasant. Zippers also make changing out a layer easy. Just open up the zipper, slip off the old one, and snap it into place on the new one. Changing out your midlayer is similar, but instead of opening up a zipper you're taking off a piece of fabric. The more pieces you have to move, the harder it is to do so safely. It's best if all your layers are identical in size so that they can be put on over each other easily. A thin, light-colored shirt makes for a safer change than a thick, dark-colored one because you can see what you're doing better. Finally, avoid wearing loose-fitting clothes as a base layer. They'll hang low on your body, exposing plenty of skin to the wind and snow. This will make it harder to stay warm. Wear something tight yet flexible, such as spandex cycling shorts or a leotard. Midlayers come in all shapes and sizes. Some people prefer to wear multiple smaller items rather than one large one. That's fine too!