Veinbuster's tip is a good one, and I'll ad a few thoughts:
First thing to do is, as he says, wipe the guitar down first. I'd use a damp (not wet! just damp!), all-cotton or microfiber cloth just to get the surface grit off, and dry with either a chamois or a microfiber cloth like one of these (the flat microfiber cloths like the ones for computer screens or eyeglasses aren't as soft or absorbent for cleaning, etc.):
http://www.griotsgarage.com/product/micro+fiber+speed+shine+cloths+set+of+3.do?sortby=ourPicks
After cleaning the guitar, try the polish in a small area at a time. Don't apply polish to the whole guitar at once. With any good traditional guitar polish (or a good fine abrasive automotive polish like Meguiar's No.7, etc.) you want to use very light, fast strokes, you don't want to rub hard. The idea is to break down the abrasives in the polish to a finer and finer powder, until it pretty much disappears. Then wipe off any excess with a clean microfiber cloth. I try to avoid using so much polish that it gets stuck in the hardware, etc. A small amount should work, rub lightly, rub quickly, for enough time to completely break down the polish.
If you use a polish that acts chemically, like Virtuoso polish, I honestly have no experience with that, but the same general principles should apply, except that you won't need to break down any abrasives, so less rubbing should be needed. Once again, polish a small area at a time, look carefully at the results to make sure you've got all the scratches and haven't left swirl marks, and then move to the next area. Avoid getting polish under the knobs, pickup rings, and hardware.
Once again, the object of using a microfiber cloth is that some fibers in cloths can actually add new swirl marks. Some people like soft all-cotton, but I find microfiber cloths like the one I linked to be even gentler and leave no swirl marks from the polishing the way cotton can. Microfibers are actually finer than cotton, assuming you have good quality cloths.
In any case, avoid polyester or poly-cotton blends, etc. No nylon cloths. They will cause swirl marks like crazy. All-cotton, microfiber, or chamois are ok.
Don't use wax on a guitar. It will yellow, and the guitar doesn't need to be protected from road grime and bird droppings with a wax like a car does.
PRS Cleaner is a very nice final step, by the way, it leaves a very nice shine after polishing.