I've been told that making sure you pee before bed is important. Reason being is that if your bladder is full, your body will isolate heat to keep the liquid warm pulling heat away from the rest of you. A quick Google search displays a very two sided argument however, I've personally found it to work.
plus getting up in the middle of the night when its cold suuucks.
uhhh, if you have warm bedding, its better to sleep with LESS clothes, counter-intuitively. Its cold at first, but heats up the space faster and hotter. I go nekkid except a toque. Pack your clothes in the bottom of the bag so theyre warm the next day. A good mat makes a huge difference as you loose tons of heat thru the ground.
In the winter I dig a tent pad out based on my ground sheet, piling snow evenly on the immediate edge to make a bit of a lip. I then pack it down evenly, and add spruce or cedar boughs from surrounding trees to cover the ground about 6" thick (try to keep any big sticks out). I then set my tent on top of that. Winter camping sucks, but its totally doable. The -25C or less hybrid or full down bag is key. I use a Thermarest Neo Air and its toasty warm. You just have to be prepared to be uncomfortable.
I used to do this every ~2ish weeks when I lived in vancouver, as I would camp on blackcomb just off a ski run because I couldnt afford a hotel.
