Keep your windshield washer fluid reservoir full of the low temp stuff.
I try to pay attention to how much snow is on the roof of the vehicle in front of me. I don't care of the guy behind me rides my @$$ hard, I'm staying way the F back so I don't get hit with any when it comes flying off.
Touchless carwashes with an underbody spray are your best bet when it's extra cold. Cheapest I found in my area is $7 - includes underbody spray, soap/water wash, and air dry. That one actually closes when it gets really, really cold though, so sometimes I have to settle for a quick diy spray n wash joint. Avoid automatic car washes with brushes and other moving material devices that contact your paint.
I've noticed some people bend their windshield wipers away from their windshields when they know it's going to snow - I assume maybe it's to keep them from freezing to the windshield? I don't have to do that because my car has a windshield wiper de-icer function, but that might be something to think about too.
And be sure to give your car a pretty good detail (clay bar and wax at least) when the weather warms up again in the spring. It's probably too late now, but that should have been done a month or two ago when it was warm enough.
07 WRX (Albins 5MT + Blouch 20G)
Jorge Carrillo Tuned (365 whp/340 wtq)