If you go camping in the desert, make sure you bring a tent that seals completely, and put your sleeping bag in the tent. Becuase the desert's usually warm (except the winter, which can be quite cold in the desert, don't be fooled), it's tempting to "sleep out under the stars." Resist this temptation.
Rattlesnakes like nice, warm, cozy spots where they can curl up. The human burrito that is a person snug inside a sleeping bag is inviting. You'd hate to wake up in the morning to find a 3' mojave coiled lazily on your chest, and none too happy that suddenly the source of warmth in the cave has to get up, fix coffee, and hit the trail.
Leave your sleeping bag wrapped up inside the closed tent until it's time to bed down. Enter, close the tent behind you, unroll the bedroll, and shake it out CAREFULLY. All clear? OK, make sure the tent is tightly shut and enjoy your rest!
Also, next morning, before putting on your boots, shake them out, too. Scorpions, dontcha know.
Also, when camping in National Park areas provided with steel food lockers in bear-travelled areas, stow and lock away the food FIRST, then start setting up camp, tents, bedrolls, campfire, etc. Bears are smart enough to wait until folks start setting up tent to stroll down and wander off with someone's pack, still laden with food, and in areas where they're "used" (relatively) to seeing people, they tend not to be too worried that you'll try and do something about it.
Warrior Poet