The gently does it approach applies to just about everything when driving in winter conditions. Pretend you have an almost full bucket of milk with no lid on it, sitting on the back seat...you dont want to spill any of it, as it will stink the car out of it!!

Leave plently of space to the car in front
Easy on the throttle
Dont jump on the brakes
No sudden inputs to the steering; slow and purposeful

Most cars we drive will have ABS, so remember that it will pulse if they activate and remember to keep your foot planted. If you've no ABS, look into cadence braking.
Weight in the back will help. A shovel and a length of thick rope in the boot might come in handy (if you have wheels you dont mind marking) for deep snow. Use the rope to tie a loop through the spokes and around the tyre in a few places on both rears, to get extra traction.