Sane -- Welcome to RetouchPro!
Lots of us lurked a little bit before joining just to make sure it was really as nice a place as it seemed. You'll find that if you post an old photo that you're working on and want some help that you'll get some folks jumping in to show their versions and some tips on what you can try. Be sure to post your retouched version and ask any specific questions that you have when you post. You've mentioned that you have already seen the challenges, the tutorials and the forums -- now you just need to pick a spot (or two or three) and jump in!