hey man, just to let you know I used to play with my thumb way around the neck too (like wrapped around the neck so that you could play the root of a bar chord with it, like hendrix). i thought there was no proper way of playing everything too. now i know it's not true with respect to form as i developed pretty serious tendonitis and carpel tunnel everywhere in my arms (on the day it started i had jammed in 3 different jam sessions each of at least 3 hours though so i was asking for it but huge hours with your hand totally tense like that everyday built it up) and I was out for over half a year and then had to start virtually all over again. really sucked. there is a proper way when it comes to stressing muscles and joints. some things aren't as serious as other though.