In this thread we discuss how we would prepare for winter operations.

Personally I would wear layers so that I could shed some and be unencumbered during the day when it's a bit warmer, and so I wouldn't sweat as much. At night I would prefer to have clothes warm enough that I could sleep next to a fire without blankets or a sleeping bag, but this really depends on the climate of the area. I would wear a couple of layers of socks, but make sure to keep my shoes loose because if they're too tight they'll just cut off circulation to the foot, and you need a space in there because it's the layer of air that stays warm, not the fabric. For food I would eat something with lots of carbs for energy, like tortillas.

I would try to set up my camp on rough terrain and in the woods to stay hidden, and make it hard for the enemy to reach me. I would also cover up any tracks I left in the snow leading to the camp.

I've also heard of a material called "icecrete" that can stop bullets. Basically it's made out of dirt, snow, water, and gravel or sand, but I'm not really sure how it's made. Anyway, it can be used in the construction of bunkers.

This is all long term, but If I were just going on a short expedition (like going to a fistfight or something) I would just wear a t-shirt and jeans. If the Roman legions could pass the Alps in tunics, I think I could handle winter fighting in a t-shirt.