However prepared you are, sometimes getting stuck is inevitable. If you do, try to get moving by clearing the snow from in front of the driven wheels. Try rocking the car back and forth with the gears if you're really stuck. If that doesn't work then you'll need some of the equipment you've got prepared in your boot. Stay dry and keep warm inside by wrapping up. Keep a window open very slightly as heavy snow and ice can seal a car shut. Run the engine periodically to keep the interior warm and the battery from getting flat - the more fuel you have the more you can run it though be sure to check that the exhaust pipe is clear and there's no build up of fumes getting into the car.
Wait with your car to be rescued, and call for help. Only get out if you're absolutely certain there's somewhere you can seek refuse. Otherwise stay with your car.