Nobody likes a know-it-all. I'm not claiming to be an "expert," just a normal guy who loves to shoot and loves to shoot competitively in IDPA and USPSA. I'm not even classified in USPSA yet. But I will be soon. IDPA has been my game for a few years now. I just started shooting USPSA matches this past fall.
In the past two years I've learned a ton from reading, from instructional videos, but mostly from shooting a lot. There's nothing more effective than putting lots of lead down range with practice drills, club matches, and major sanctioned matches. You can read all you want and amass a lot of head knowledge about the sport. But to really improve you just have to shoot and shoot and shoot so that drawing, aiming, moving, reloading, etc. all becomes second nature.
And if you want to learn how to shoot well and win, don't worry too much about having a slick, expensive gun. Put that off for a while. Buy ammunition. Better yet, reload your own ammo so that you can unload 200-300 rounds in a practice session once a week. Or so that you can shoot your local IDPA club match one week, participate in a steel plates match the next week, join the USPSA guys the week after that, and so on. Get a reliable production pistol (Glock, M&P, Springfield XDM, etc.) and then just shoot it as much as you are able given your time and budget.