1. Wear multiple layers of clothing, such as a base layer, a mid layer, and an outer layer.
2. Use a sleeping bag rated for cold temperatures.
3. Place a barrier between your body and the ground, such as a camping mat or a blanket.
4. Bring along a hot water bottle or a hot rock to place in your sleeping bag.
5. Use a heat source such as a campfire or a propane heater.
6. Stay hydrated and eat warm foods to keep your body temperature up.