Although a number of medical professionals still recommend applying a tourniquet to rattlesnake bites (and then briefly releasing the tourniquet every 15 to 20 minutes), Tony Nester, the author of Desert Survival Tips, Tricks, & Skills (Flagstaff: Diamond Creek Press, 2003), writes that most of the doctors he spoke to advise against applying a tourniquet (it simply concentrates the venom in the tissues immediately adjacent to the bite). Your best treatment is to get to a hospital or clinic as quickly as possible: do not delay.
Nester says that two important rules of desert living are 1) “Don’t put your hands where you can’t see” and 2) “Vigorously slam your boots on the ground and shake clothes before you put them on.”
Watch out for Gila Monsters, Africanized Bees (Killer Bees), Black Widow Spiders, Scorpions, Rattlesnakes, and Coral Snakes. Wear sturdy hiking shoes or boots. Do not hike alone. Carry a cell phone, an ultralight emergency blanket, snacks and at least two liters of water. Always let a friend or neighbor know where you are going and when you expect to return.
You will also want to read The Ultimate Desert Handbook : A Manual for Desert Hikers, Campers and Travelers by Mark Johnson and 60 Hikes Within 60 Miles: Phoenix: Including Tempe, Scottsdale, and Glendale by Charles Liu.