Start competing.
Thats it, really. First, be prepared to find out you suck. Man, did I ever. then you'll slowly see your scores start creeping up. Then youre in B-class and fighting to make A-class. Try to be on a squad with shooters that are better than you, since nobody wants to be the worst in anything. Watch the better shooters and ask questions- you'll be surprised how much the good shooters are willling to share. Next thing you know you're practicing with one of them, going to matches outside of your area, taking up reloading. It's a journey.
I'd suggest taking some competiton oriented classes. My first clinic made a huge difference in my abilities. Check out some of Lurpers videos on here as well.