Just keep practicing.. Everyone has to start somewhere. Really, everything related to graff/abstract art is molded off of a trial/error basis, so you're fine.
I like the strong piece the best: Pretty proportioned, except the S, but it boasts a better letter structure than a lot of the stuff I see on here. I would use that piece as the basis of building your own style. Keep up the good work, though!
@ Devour,
Dope stuff.. I really don't think you should be in these toy threads; you'll get much better advice from the other new sketch threads.
@ somekat,
Pabst, right?
Same as ^^ above, really. Maybe work on your handy's a bit.