Finding a good instructor is probably the hardest thing to do. By "good" I mean someone whose head is in the same place (musically) as yours and can understand the process by which you learn. I haven't the time for setting up regular lessons with someone and I've found that for me books and CD lessons are useless. I really need to see what the person's hands are doing to understand how the song is played. If it weren't for the internet my guitar would probably be decomposing in a closet somewhere. Firstly, Breakdown Way is incredible, in that you've got world-class instructors taking apart songs and showing you everything they do, as well as alternate ways of doing it. I can't recommend it enough. If, in these tough times, the $14.99 a month is too much, I've found there's a lot of things out there on YouTube. Everything from people giving actual (free) instructions to people just performing. I've learned whole songs just from watching someone's solo performance where I could see their hands and figure out the chords.
I don't read sheet music but can de-cypher tab. The main problem with tab is that it's seldom accurate. It reflects how someone else plays the song, which is not often the same way it's played by the original artist. I tend to look at tab as guide to get me in the neighborhood of where the song is played, and play around with it until I get to a point where a) it sounds about the way I want it to and b) I can play it comfortably.
And there is no substitute for practice. I've found that my learning curve is not very smooth in that I'll hit a wall for a while, not really seeing any improvement. Then I'll hit on a song I hadn't played before and sit down to learn it and find that I can actually learn it in a fraction of the time it would have taken me a year or two ago. After learning a few new songs I then find that going back to the ones where I hit the wall I find I can play them much better than I remembered.
Hope in all this rambling you can find something of value. One thing that keeps me going is part of an interview I read with T-Bone Burnett. The interviewer was asking him how he developed his style of playing. T-Bone answered that he started out trying to copy Ry Cooder and couldn't so this is what it came out sounding like. I suspect that most acclaimed musicians probably 'came up with' their sounds by trying to copy others and failing. After all, how many guitarists have achieved true fame by "sounding exactly like" someone else?