I wear my insulating layers beneath my wind layer (which does double duty as breathable raingear). I figure the idea is to create a dead space for the air to heat up... I think some people like to wear their layers on the outside to prevent them from getting moist with sweat, but I just wear less insulation underneath instead. I've even hiked around with nothing under my wind layer except undies. It feels weird for the first minute, but once you stop and get chilled you get to put on clothes that are pleasantly dry instead of sweaty.