When pitching your tent in the snow you need to concern yourself with three things: avoiding a dangerous site, creating a firm surface, and securing your tent so it doesn't collapse.

Steps
1. Avoid choosing a site with trees overhead that may dump snow on you during the night. Also stay away from nearby slopes that may be prone to avalanches.

2. Stomp around the area where you plan to pitch your tent, preferably wearing your snowshoes or skis, to create a firm table of snow. This is also known as "tamping," and will prevent you and your tent from sinking into the snow once you crawl inside your tent.

3. Melt snow on your camp stove and pour the water over the area if the snow is particularly fluffy and soft.

4. Smooth the melted snow out so that it is as flat as possible. Wait about 30 minutes for it to harden before pitching your tent.

5. Stomp down the area around your tent as well so that you can move about freely without wearing skis or snowshoes.

6. Use a winter tent specially designed to withstand winds and the weight of accumulated snow, and stake your tent down using snow stakes.