I'm pretty much at the stage of learning about tone and tweaking. I feel that the biggest mistake people make is not making up their minds about what they really want, and just going through random gear in hopes of finding 'that magic tone'. It's important to make up an image of the tone that you want mentally and work on from their and/or use reference material. If you're an old school guy, you shouldn't bother about plugging in a tubescreamer in front of your amp, and hence the all-mighty chug, and vice versa. Or I could be totally underestimating the tubescreamer by saying this, and not really understanding what it's really capable of - As I said before, I'm still learning.
+1 to what Marcus pointed out. Stick to what you have and work on from there. I know many people who are simply frustrated with their tonal sense just cause they have a tendency of finding faults. Ponder upon this. It's human nature for that to happen. Once you keep on convincing yourself that you're yet to find 'that magic tone', the universe says 'your wish is my command' and thus, you're unsatisfied. I'm sure we've all heard super-expensive productions in which we aren't happy with the guitar tone. In my case, I downright hate the Clayman tone. So yeh, don't try to find faults - and I'm sure you wouldn't find any unless there's some major goof-up. Work from an audience's point of view, not from a producer's point of view. You won't regret it.
Okay, I'll cut the crap.