After a dear elderly friend got frostbite after she was stranded on a highway in her car due to an accident that stopped traffic for hours during a snowstorm, I learned some items that every car should have during the winter. They are a large tin can and substantial candle and matches to maintain warmth for longer periods of time.
Since it is recommended that you don't leave the car idling for long, instead turn off the car and light the candle and place it in the can and hold it. It will keep you and your hands warm while waiting. It is also recommended that you open your window a crack every once in a while. A spare blanket, heavy warm gloves, water and some healthier snack foods (bag of nuts, granola bar, etc) should be included in your kit.
It is also recommended that if you are ever in one of these situations (and for most accidents), you should not get out of your car. More people are hit by other drivers during these snow and multiple pile up type of events than if they just stayed in their cars.
My dad suggested I take a piece of my gum I was chewing and press it over the key area, which I did. The next morning, I barely bumped the small frozen solid patch of gum off the keyhole area to find my key area was not frozen!
In the winter, my hands occasionally become so cold that it is uncomfortable. To keep a good grip on the steering wheel and stay warm at the same time, I tried a pair of fingerless gloves (aka gauntlets).
Besides the usual guff about gearing down appropriately for an automatic or manual transmission, why not reveal the following secret? Use the brake pedal BEFORE you enter curves, not in the curve!
When going into extreme weather conditions, have your automobile checked out thoroughly. Don't cut corners if possible. It's for your own safety as well as for others.
When snow and ice are on the ground, you see a lot of people loading the bed of their pickup truck with heavy stuff to help with traction on the slippery roads. Please remember that whatever you have in the back of the truck can go flying if you are involved in a crash.