Well, for the most part of my life, I used ro drive under the conditions like the one that recently swept the entire Northeast, and I did so from mid October to mid April, so that's my 2 cents:
General rule - try to apply brakes as less as possible. MTX - brake with lower gear. With ATX - try to simulate ABS - press the pedal intermittently several times.
MTX - start with 2nd. ATX - some cars are equipped with "W" (stands for Winter) mode, enabling to do the same. Dunno about starting ATX from 2nd - ATX's 2nd is not exactly the same 2nd
Don't think that by driving 25 miles per hour you are choosing the safest driving mode of operation, as higher the gear is - more stable your car is (of course, within the limits of common sense)
Try NOT to own a rear wheel drive
- my wife has major probs driving her Merc at the weather like this
Try NOT to drive parallel to any other car in the next lane - drive ahead or behind - less chances of being hit by another car (applicable in all weather conditions)
If your car skids - NEVER try to turn the wheel in the opposite direction as your immediate reaction tells you to do - it will only increase the spin, try to wheel in the same direction and maneuvre
Try not to drive next to shoulders - the recess characteristic for many shoulders creates the prob of ice below the snow - scary shite
When there's appropriate space with no other cars - such as empty parking lot - try to abruptly brake your car a coupla times - it will give you a feel what you can expect on the road and how to prevent it