* you have a full tank of gas.
* you have a fully charged cell phone.
* you tell someone when you are leaving, where you are going, and what time you should arrive.
* you have plenty of warm clothing.
* if you become stranded, you may be there a while. Make sure your exhaust pipes are not blocked and run your vehicle to stay warm.
* you take it nice and slow.
* the best preventative measure is to not get out in this weather.