[trjordan]

Without talent, you must practice. Take a song you don't know how to play, and start to figure it out from a recording. Once you've mastered that song, pick another one. There's no secret to any of this.

I've have no natural talent for music, but I put in the hours. When I was 16, I was cut from my high school musical for my inability to sing back a note played on the piano. I took voice lessons, got a few chorus roles, and kept working at it. Over the course of college, I got a few friends together and practiced a few hours a week. By the time I got to senior year of college, I got the lead in the play and was performing solos with my a capella group. These days, I sing with a barbershop quartet - understanding the harmonies there, let alone reproducing them, was unthinkable 5 years ago.

If you don't have the talent, you've got to work at it. It will pay off, I promise.

[jerf]

I would add a few more points: I forget the exact term, but be sure to engage in purposeful practice, always challenging yourself with a song just out of your reach. Start as easy as necessary and work up.

It would be helpful to do some songs that you can get the full score for, so you can do concrete validation of your correctness. However, be sure that they are the full, true score; grab a Guitar book of Beatles songs, for instance, and they're likely to be simplified in a way that won't help on this task.

[unalone]

This right here is worth repeating. Never pick something you're certain you can do. Go for things just out of your reach. Pick things that you're going to have to strain to do. Do this again and again, and every time you get a bit better.

Occasionally, attempt something far beyond your reach, just to remind yourself of what you're striving for.