It's easy for people to get hurt. Pick a hike that is accessed by a road your vehicle can handle. Don't try to negotiate boulders if your car doesn't have four-wheel drive. Break in boots before heading out on a major hike. This is one area where animals have the right of way.
Hikers come next, and mountain bikers yield to both.
Don't pet the cholla. This stuff breaks off when brushed and adheres to clothing and exposed flesh. Extracting spines is painful and time consuming. Take a comb along to yank out large pieces, tweezers for smaller spines. Duct tape pulls out tiny stickers.