On nearly every trek and walkabout I've done in the desert Southwest, I have encountered a rattlesnake, especially under and around rockpiles as this is where rodents also dwell.
While writing a book on desert survival, I spoke with the fine staff at the University of Arizona Toxicology Department, who said your best treatment for rattlesnake bite is to grab your car keys and head to the ER. Using suction devices, snakebite kits, and Hollywood methods of cutting and sucking will only waste precious treatment time that should be spent at the hospital.
In the field, stay calm, wash the wound, stay hydrated, and make a call for help if possible, but otherwise, if you're solo, plan on walking slowly back to your vehicle and driving out. Don't use a tourniquet or ice, just plan on getting to a hospital--remember, if you were actually envenomated, time is tissue.
Around 25 percent of rattlesnake bites are dry (without the snake envenomating you), and the good news is that rattlesnake bites are rarely fatal. According to the Arizona Game and Fish Department, there were 1,912 people bitten in Arizona from 1989 to 1998, with only four fatalities. One thing to note is that kids are at higher risk from any venomous bites because they have a smaller body mass to absorb the toxin. Interestingly, the pattern associated with rattlesnake-bite victims is that they tend to be male, 18-35 years of age, and intoxicated. In other words, the snake was provoked.
Bottom line: Carry a walking stick and remember the golden rule of wilderness travel--don't put your hands and feet where you can't see!