Windshield washer fluid. Mine froze last week, I just bought this truck and haven't gotten to checking everything out. Not all fluids are good below freezing. Check your coolant, make sure it's good to below zero. I froze a block at O'Hare, 200 miles from home, it was inconvenient.
Wipe down all your foam door seals with silicone, I just spray it on a cloth and wipe. That keeps any moisture from sticking and freezing the seal to your doors. Squirt a little WD40 or similar in the locks, even if you don't use them, you don't want them freezing. Rubber floor mats are helpful for keeping things neat. Good wipers will be more important in snow. Snow brush and scraper. Wax it in the Fall. Some people wax their lights, that helps keep ice from sticking. Rain-X the windshield and mirrors to make it easier to remove snow and ice. My manual cautions against Rain-X on the mirrors because they're already hydrophobic coated, maybe someone can chime in. I don't have heated mirrors, you probably do, so don't bother doing them. Learn to leave your wipers up when a blizzard is coming, you'll see everyone else doing it. Tire pressures go down in the cold, you'll need to check them as winter begins.
Synthetic oil will give easier starts when it's really cold, that's my main reason for using it. Even heavy synth starts easier than dino. And I mean real synthetic, not a blend or even the "new" Mobil 1, but Mobil 1 extended performance or Shell Rotella T Synthetic.
