Find out the forecast temperatures and make sure you have a suitable sleeping bag for the coldest nights, make sure you have a hat; multiple layers are warmer than one thick sweatshirt. Emergency silver "blankets" are a good precaution.
First, know that you are going to be cold. Second, know that you are going to be COLD. Therefore, bring twice as much food as you would in the summer as your body will need the calories to keep your core temperature up.