1 - If your battery is on the edge, replace it now.
2 - Cold temps lower the air pressure in your tires, air up when the cold hits.
3 - Windshield washer fluid (and headlight washer if you have them) make sure you have fluid designed for the lowest temp expected.
4 - Check coolant for proper expected temperature range.
5 - Have some commonsense "emergency" supplies in the trunk (blankets and the like).
6 - A fresh coat of wax or other paint sealant can't hurt.
7 - Keep an ice scraper/snow brush in the car. A pair of gloves or mittens in case you don't have them with you all winter anyway.
That's about all I can think of now. Luckily my Z hibernates but I do have to prepare other vehicles...I hate winter !