As a base-layer I would recommend a high wicking material for your T-Shirts or leggings, such as merino wool, as it will wick the body moisture away from your body and your clothes, which means that even though you may be sweating your clothes won’t get wet. All my trekking tops are from Icebreaker. Their clothes will keep you warm when it is cold and cool when it is warm. They also look pretty, which is quite unusual for technical clothing.