I'd add a few items to that list DS:

-If you have snowchains for your vehicle, try putting them on at least once BEFORE you go driving in the snow. If you're sitting in the middle of the road, stuck and wanting help to figure out that you bought the wrong size, I will laugh and drive around you.

Know whether your vehicle is FWD, RWD, 4WD or AWD. Tire chains go on the drive wheels (Durrr, but I've seen people stuck with the chains on wrong. I laughed and drove by). If you own a 4WD or AWD and need chains, put them on all four wheels to avoid damaging your transfer case. You may also chain up all four wheels on a 2WD for more control. Steering>Traction. Better to be stuck than careening towards your demise, eh?

-When buying studded tires, buy all four. The last tire shop I bought studs at told me it is against their policy now to sell just a pair even if the customer requests it because control is compromised. Your life is worth more than a set of tires IMO.

-Take the time to clean your ENTIRE windshield off, as well as the back window, mirrors and side windows. It's also a good idea to clean off your headlights and turn signals. Things like seeing and being seen become more important in the snow, not less. Add an ice scraper and/or a handbroom to your essentials list.

-Keep your tank topped off at a higher level. My personal limit for Winter is 1/4 tank. You never know when you'll be stuck yourself or stuck waiting for someone else, and your life may depend on your heater working.

-Don't help people get unstuck, no matter how badass a 4WD you have unless it's a real emergency. Offer to call a towtruck instead. It may seem mean, but I've seen extractions go awry in very bad ways. Not worth it IMO.

-Carry water in the passenger compartment. If you get really stuck, you'll appreciate your forethought.