One thing I noticed after watching the red hot chili peppers:
When it comes to rhythm, less is more, and there is no substitue for good timing. Use a metronome.
Also, IMO, when you enjoy playing, you sound better. If you don't enjoy playing with huge strings and really high action, then you're going to sound bad. Music is about passion. The only famous guitar god player that I can recall that used absurdly heavy strings was stevie ray vaughan. Duane allman, Eric Clapton, Jimi Hendrix, B.B. King, Brian May, and now Billy gibbons all use what would be considered light strings. So, before you raise your action 2 1/2" off the fretboard and switch to 13's, spend some time trying to get a good sound out of what you have.
Also, vibrato is underrated. Most people just do it without giving it much thought, but it really deserves as much attention as you can muster for it. If you can make the high notes sound like a singing woman, then you're going to sound good no matter what you're doing.
The average person doesn't pay as much attention to your sound as you do. Quit worrying about your sound and start worrying about what you're playing. Like I've heard before, it's not what you play through, it's what you play through it.