1. Get a qualified instructor. You can go to
this page for a list of BCA certified instructors. This will help you get your mechanics strightened out before you develop too many bad habits. Also, you'll get a pretty extensive primer on the physics of the game. It's not cheap, but it will save you tons of time later on.
2. Any of the books/videos mentioned are good, but to improve most quickly, I recommend Bert Kinister's 60-Minute Workot for 8-Ball and 9-Ball (
www.bertkinister.com). Practice that stuff and your game will improve dramatically. Bert has some other worthwhile videos out there, but some are crap, too. In general, the lower the volume number in his series, the more good info there is and less BS.