I've done a fair bit of cold weather camping (and warm weather!) - I've camped at the Elefantentreffen for 4 out of the last 6 years and in 2011 went motorcycling and camping in Norway. in February. in -15 to -20 deg C.
I really enjoy camping in the snow.
http://www.sweller.co.uk/norwaybound2011/#DSCF6289.JPG (I was on the old Armstrong).
Elefant 2010:
https://www.facebook.com/media/set/?...1&l=f33670ed67
My top tips are:
Decent tent with Alloy poles (fibreglass break at very cold temps)
Coleman Dual Fuel stove is the best and most reliable I've had (I've tried a few and seen others use theirs, the Coleman just works but it's a bit heavy) - gas is utterly useless under freezing.
For sleeping:
Thermarest - this is a must.
I use an Army surplus cold weather sleeping bag. The absolute ********.
Like this:
http://www.ebay.co.uk/itm/British-Ar...-/171206597930
I find sleeping in socks and thermals allows for that extra few degrees chill
Another top tip: make sure you keep your boots in the tent as if you drunkenly leave them outside they freeze solid overnight and you can't get them back on....