As well as the threads here, look on You Tube...3m have a series of very good instructional videos that cover everything from large flat panels to intricate curved shapes, cut-outs, bike tanks and double curves, with lots of tips which make a difference.
I've not done a pannier but I have done a good few smaller items including a dash trim with many different curves on it.....If I was doing a pannier, I'd definitely want a second pair of hands to assist, as it's fairly easy to get into a right pickle......that can always be resolved, but it gets quite frustrating.
A decent hair dryer is fine for wrapping, you don't need a full on heat gun, and although you won't need it for a pannier, the 3m pre-treatment stuff which effectively adds glue to the complicated inner curves will be on my shopping list when I do anything more complicated than I've already tried.
As with all body work or painting or anything similar, preparation is absolutely key........I used rubbing alcohol from Boots to totally de-grease my surfaces and beware of any level deviations....the Tuareg sticker that was in the middle of this simple piece is still very visible, even though I rubbed it down to what I was expecting to be fine....I quite like having the 'ghost'[ of him still there though