Rule #1--Most important rule EVER:
If you are not comfortable driving in adverse weather STAY OFF THE ROAD. DO NOT DRIVE. NO arguing, no qualifications, no s***. If you're not comfortable behind the wheel in snow, you have no business attempting it.
--However quickly you think you can stop, leave at LEAST twice that distance between the car in front of you. And, conversely, keep that following distance in mind when merging with traffic...don't be the d!ck who eats up decent drivers' safe following space because he's too stupid to find a proper opening. Panic maneuvers are a lot harder to pull off when steering traction is limited, so try even harder not to have to make them.
--Don't go slower than necessary! Sure, driving too fast is dangerous, but driving too slow in slick conditions creates a moving chicane. Passing and changing lanes in heavy snow can get hairy with rutted and unevenly distributed snow. When people have to move to go around you just to travel at a safe speed, you are chancing a lot of accidents for nothing.
--PLEASE at least TRY to maintain some semblance of lane organization. Yes, I KNOW you can't see the lane lines through snow. You should still be able to tell where you are on the road if you have 2 synapses to fire across each other. DON'T just follow the pre-worn trails of the other idiots on the road. They, as their namesake indicates, are idiots. Drive in the lane you need, just like normal. The more traffic spreads out, the greater the area of road that gets worn free of snow will be.
--Begin slowing before you think you need to. I promise, you've misjudged your stopping distance. Leave some room for error. That kid at the crosswalk and my rear bumper thank you.
Related to this one, I've made a habit of watching cars behind me and stopping accordingly. I let them follow too close and plan to stop short, so that when THEY can't stop, I've got somewhere to go to get out of their stupid way.
--Use your damn headlights. I don't care if its 2pm. It's snowing, and you're difficult to see. Turn your damn lights on our I'll turn 'em on for you and tear off the knob and shove it up your a** with help from my size 13.5 steel toe boots.
--Try to remember that stopping, braking, or even just letting off the throttle are NOT the end-all, be-all of "oh s*** what's happening" panic maneuvers. In traction-limited situations, varying tire rotation speed abruptly is likely to just make things worse. Try to keep a clear head and react SMOOTHLY. If you loose steering traction and start understeering, don't hit the brakes--you already lost traction, and there's none left to stop with. Steer back and regain some control.
I think that's it for my list for now.