Go to a professionally-run range and/or pro shop. This is all great advice in this thread, but having someone actually on-scene critiquing you is worth 1000 pages on this forum. They'll see little things that you're doing that you're not even aware of...and therefore won't know to correct. When I first learned to shoot a bow, I didn't have great instruction, so had a lot of bad habits to correct further down the line. Had I gotten a good start, I could have really shortened the learning curve.