I'd do bumpers and rock sliders first. You can get into pretty deep sh*t in a stock toy if you're a good driver and you'd hate to hurt the body when it wasn't necessary.
Yep, agreed. And my DD that still gets wheeled has a front locker, and open rear. Reason being, I wanted a true open for the street, no popping from a quick locker, and the engine weight really helps to utilize full front traction. So...
1. Armor- Bumpers, sliders, skid plates
2. Chunky 31" tires
3. Front locker (if the rig is already solid front axle, otherwise, rear locker)
4. Crawl box, cause you can have a lot more fun with the control of the low low range
Of course this is all assuming the truck in itself is good to go, engine, brakes, steering being the most important to a great day on the trail