If you can't remember when you last replaced your windshield wipers, it's time for new ones.
Make sure your windshield washer system works and is full of an anti-icing windshield washer fluid that includes chemicals to keep it from freezing up in the reservoir, as well as on the windshield. Apply a water-shedding coating (such as Rain-X) to the outside to assist with visibility in rain and snow.
Before you get behind the wheel, be sure to remove all snow and ice from your car. Don't just clean the windshield: Make sure you also clear snow and ice from side and rear windows, as well as the top, sides, and trunk of your vehicle. Clumps of snow falling off your car as you drive can be hazardous to drivers around you.