How do I stay warm camping in winter

make a fire, be sure to eat before you get too hungry, have a special set of dry clothing for sleeping. make sure to always be just warm enough, not too warm, when outside in the cold for long time the worst that can happen is to sweat in your clothes and end up with wet clothes, then you can die. when I am outside for long I try to keep a little cold rather than a bit too hot. have a freezing weather sleeping bag. if you dig a shelter in the snow or make an igloo you can keep a candle burning to make just a tiny bit of heat. I've never actually slept outside in the winter but I've talked to people who have.