Recharge or replace weak batteries. Have your alternator or generator and voltage regulator checked as well. To avoid skids on slippery surfaces you need to prevent the wheels from locking when the brakes are applied suddenly. Brakes should be checked and, if needed, properly adjusted to ensure equal braking. Make sure your tires are properly inflated and in good condition.
Many drivers find that a set of all-season radials works well.
The next step up is a good set of snow tires. Chains provide the best traction in severe snow and ice, but should only be used on all four wheels. Have a mechanic check your exhaust system for leaks. Carbon monoxide is odorless, very hard to detect, and it can kill. If your car is stuck in the snow and you have the engine running, open a window slightly and clear snow away from the exhaust pipe.