Shelter - Find a place to shelter your tent from winds. I know it may be hard to do this in a desert, but try to make camp on the edge of a dry lakebed, not in the middle. If the wind seems to be coming from a particular direction, park your vehicle to block the wind.

During the day you keep warm by being active - hiking, dirt biking, etc. At night when it gets colder and sleep beacons you is when you need to be prepared.

Bedding - Make sure you bring lots of warm bedding. I usually take a 0° F rated sleeping bag, a sleeping pad, an extra blanket and a summer rated sleeping bag. Make sure you have lots of padding between your sleeping bag and the ground of your tent. If you don't, the cold ground will suck all the heat out of your body while you sleep! Burrrrr!

Sleeping - Before you go to bed, put on your long underwear, wool socks and a wool hat. Your body loses lots of heat through an exposed head. If you wake up cold, put the extra blanket or summer sleeping bag on top of you or another layer of clothes such as: sweat pants and a sweat shirt. If you get too warm, vent your sleeping bag by opening the zipper, or vent yourself by taking off your wool hat or a layer of clothing. The key is to keep warm, but not to sweat. Perspiration will make you wet and cold. If this happens, peel off your wet clothes and put some dry clothes on and start again.