If it’s really cold I’ll do 3-4 layers. Typically for my legs I’ll do Long John’s, then a pair of sweats, then my jeans.
For my torso I’ll also use a Long John shirt, then a long sleeve sweatshirt, then a hoodie, then a Carhartt jacket. Also, always take a few extra pairs of socks, if you’re feet get wet from sweat, they’ll get very cold as soon as you slow down or take a break.