Fantastic advice Cannibal. As temperatures get seriously cold, the rules of the game change completely. A couple of items off the top of my head:
- You must have adequate insulation in seriously cold weather. Your body can not generate enough heat to keep warm if most of that heat isn't being trapped and held. If you need a fire for warmth, you are under-insulated.
- Stay well hydrated and fed. Your body is your main source of heat in the wilderness. If your core temperature drops or your furnace isn't pumping out the heat, your in trouble.
- Safety in numbers - whether it be hypothermia, frostbite, avalanche, etc., your only realistic line of safety, support, and rescue are the people that are with you.
- Learn from experience - it is great to talk to people who have experience, it is far better to go out with people with experience. No need to learn deadly lessons on your own. Besides, if they are going with you, they will be much more motivated to make sure you are adequately prepared when they are on the hook for getting you through it.
- Take what you think you need and have more gear in reserve. If you plan on using every bit of insulation/clothing for the expected weather, you will be in real trouble when it is 20*+ colder than anticipated.
- Have a bailout plan and be willing to use it. Don't wait too long to decide things have gone south.