Digits such as your fingers and toes do not do well in freezing temperatures. If they freeze, you now have frostbite. So how can you avoid it and what do you do if you get it?
No one intentionally wants to get frostbite. Modern clothes, gloves, and gear are helpful. Just a few decades ago, Frostbite was a much more common problem.
If aliens described what a Human body was, they would call us “Bags of water.” Every cell in our body contains water. When it gets too cold, water freezes. If your body cells freeze, then Frostbite becomes a problem.
The worst Frostbite outcome is Debridement, cutting away dead tissues, or amputation, removal of fingers, toes, ears, etc. Once you get Frostbite, it becomes easier to get it again.
When your extremities get cold, and freeze, you will lose feeling and movement. Tingling, like pins and needles is likely. The skin will turn waxy, white, or red. Burning pain is also a symptom. If the areas become frozen, they will die. Infection will set in, and tetanus becomes an issue. With decreased oxygen to the skin, gangrene sets in and the skin turns black. Removal is now the only option.
Prevention is easier and smarter. Carry, and wear, multiple sets of gloves. If a pair gets wet, put on a dry set. Same with socks and your toes. Wearing a polypropylene pair of wicking socks will keep moisture off your skin. Limit your time outside. If it gets too cold, warm up. Stay hydrated and fed, without using alcohol. Booze will help you lose the frostbite battle. If you wear cheapo gear, you will pay for the mistake when you need it the most. 
If your toes and fingers get too cold, warm them up slowly. If you hold them too close to a fire or submerge them in hot water, you can burn yourself. The nerves are slow to function and will not tell your brain the water and fire is hot until it’s too late.
Place your fingers under your arms or in your crotch. Keep your fingers and toes moving. Blood flow is essential. Warm towels help. Handwarmers are also a good idea. You will slowly gain warmth back to your extremities, but it will be uncomfortable. Have a friend rub and massage the freezing areas.
Using a good hand lotion is helpful. Apply it to your feet, face, ears, and extremities. Make sure that your gloves/ boots fit properly and are not too tight. Hats are a no brainer. I use a Capuche, which is like a balaclava hat but made from polar fleece. Avoid cotton clothing. Go with arming synthetics or wool.
Stay warm!
Montana Grant
