Check your car battery for loose cables, acid build-up and fluid. Make sure belts are tight, not cracked. Replace warn windshield wipers and add no-freeze fluid. Don't forget to stock you trunk with blankets, food, a first aid kit and a flashlight, in case you get stuck. A half empty tank allows condensation to form and freeze, leaving you stranded.
Ice can be especially hazardous.
If you have to walk across icy areas, make sure you wear shoes that will give you good traction. Go out during the day. You're more likely to slip on ice if you can't see it. Stay off the phone during a storm. Lightning can travel through the phone lines.