Going hiking in the American Southwest (New Mexico, Arizona, Utah, Southern California, West Texas) can be a beautiful and rewarding experience, but it can also be dangerous if you don't come prepared for the hazards of the desert. If you are used to hiking in other parts of the country, you may be ready to jump into the wild here too, but there are some big differences you should know about. Many people have died by not being prepared for the harsh environment that hikers can encounter out here. Make sure you are not one of them by following these rules for hiking in the Southwest.
Stay hydrated! Drink water before you go and bring way more than you think you need. Leave some in your car for when you get back. This is really important!
Start early, or late. You want to get out there long before it gets hot. While this is mostly important in the summer, temperatures can get very high, even in other seasons, and baking in the sun will certainly reduce your enjoyment. During the summer months it is especially important to get an early start, so you can be finished before the heat becomes too sweltering. Or wait until early evening when it starts to cool off.
Watch for elevation. Though it isn't a problem for many, some people find the high elevations require some adjustment. If this is your first time hiking out here, you may want to give yourself an acclimation period, just going for short jaunts at first until your body adjusts.
Keep track of the way you came. When you are hiking in the woods, it is usually no problem to see the trail; it is pretty obvious when there is a clear path through trees and underbrush. In the desert, though, it can often be difficult to tell what's the trail vs a dry gully or animal track, so be sure to pay close attention to where you came from. Keep an eye out for cairns (stacks of rocks) or other ground markers.
Watch for snakes. Most wildlife (including snakes) will actively avoid you, but it is still a good idea to keep an eye out for snakes, as many are venomous. The last thing you need when you are hours away from help, is to be bitten by a rattlesnake! Keep an eye out for where you are walking, and if you see one, give it plenty of room. Listen for the tell-tale rattle, and watch out for likely resting spots. If it is cool, they will want to hang out in a warm place; if it's hot, they will seek out cooler areas. If you see one, pause, and the slowly back away. If the snake is in your way, just stomp the ground or use a stick or rock to make vibrations that will warn the creature away. Please don't kill the snakes!