It depends on what vehicle you are wheeling, how big a tire you are going to run, where you are wheeling and if you will always be wheeling with at least a couple other rigs. My first real wheeling rig was a full size Bronco.
Here is the order in which I built it:
1) 6"Lift, 36"tires, wheels
2) Lockers
3) We don't need no stinkin lights
My second wheeling rig was a Samurai. Here is the order in which I built it:
1) 2.5" Lift, 32" tires, wheels, 6.5:1 TC gears
2) Welded rear
3) 34" tires, locker in front, chromo shafts
4) Full cage
5) Winch
6) We don't need no stinkin lights