I'll second the recommendations above: get one of the classic instruction books on the game, buy a DVD and watch it over and over (and try the shots yourself), find an instructor/mentor, and practice, practice, practice. Shoot positional drills. Set reasonable goals for improvement.
Any of several books would be helpful. To find a good used copy of a book, check out
addall.com (a site I'm ever thankful to Bob Jewett for mentioning in some other post). Although I post Amazon.com links below, if a book interests you then check addall.com to see if you can find the book at a cheaper price or better condition.
http://www.addall.com/
If you like to read, there's no shortage of books to buy, and if you search AzB you'll find a lot of recommendations. You can learn quite a bit from just one book. You could pick just one book that suits your learning style and work with the book for a long time.
The
8-Ball Bible by Robin Givens, already mentioned above, is a great book. It includes a number of examples of table layouts with runout patterns. The book includes information about diamond systems and kicks. This book is a good candidate for all-in-one instruction.
Also check out
Byrne's New Standard Book or Pool and Billiards. It includes a series of 10 drills that help immensely. The book
Byrne's Complete Book of Pool Shots: 350 Moves Every Player Should Know cover a variety of situations (some rare, but good to know) that can help you out of a bind.
http://www.amazon.com/Byrnes-Standard-Book-Pool-Billiards/dp/0156005549
http://www.amazon.com/Byrnes-Complete-Book-Pool-Shots/dp/0156027216/ref=pd_bxgy_b_text_c
Another classic is
The 99 Critical Shots in Pool by Ray Martin. For compactness it's hard to beat. It's a slim book, but could keep you busy for several weeks.
http://www.amazon.com/99-Critical-Shots-Pool-Everything/dp/0812922417
Phil Capelle's
Play Your Best ___ books walk the reader through a variety of scenarios. The Capelle books that I have are packed with diagrams, and his explanations and copious examples help train you to think through patterns again and again.
http://www.amazon.com/Play-Your-Best-Straight-Pool/dp/0964920425
AzB's own
David "Blackjack" Sapolis has a book that discusses patterns in 9-ball. His approach in discussing each and every shot in a layout is easy to follow. Reading the book feels very much like listening to him talk. Feeling comfortable with a style of instruction can be a big help.
http://www.lulu.com/product/paperback/lessons-in-9-ball/2041046
Blackjack also has a set of videos available on YouTube:
http://www.youtube.com/user/BlackjackDSapolis/featured
You might start with the Blackjack's video "Toss-Up End Patterns":
http://www.youtube.com/watch?v=wmaqaHy1h2U&feature=BFa&list=UU93yNi2Y9D_TOO_tatwlM7A&lf=plcp
Dr. Dave has instructional material that could keep you busy for quite a while: books, articles, and DVDs. His instructions are simple and straightforward. Your pattern play and precision will improve quickly by studying the various tricks and rule-of-thumb calculations Dr. Dave explains, such how the cue ball's angle of approach to an end rail determines where the cue pall passes relative to the center of the table.
http://dr-dave-billiards.com/
Dr. Dave offers gobs of free material. Free is a good price.
http://billiards.colostate.edu/bd_articles/index.html
Bob Jewett's articles for
Billiards Digest and other publications include lots of handy tricks, drills, and advice. If you search around AzB for technical explanations of various phenomena, you'll find that Bob is often the one to provide a clear, succinct, and accurate answer.
http://www.onthebreaknews.com/JewettIndex.htm
Joe Tucker has excellent instructional material at good prices. The
Guaranteed Improvement DVD + practice book is a great combo. The practice book can lay flat on a rail or nearby table as you work your way through drills and track your improvement. Some drills require specific setups that you must work through--a great way to learn patterns. Watching Joe's practice DVD is engrossing: you can see how much effort and thought he puts into each segment.
http://www.joetucker.net/
Pleasures of Small Motions by Bob Fancher is the best little book about the mental game, and also provides great advice about effective practice. Joe Tucker also has good advice on how to practice.
George Fels, another AzBer and Billiards Digest columnist, is another fine source for information about patterns. His advice that "you're probably hitting the ball too hard" should seep into every pour of your being. A lot of players grew up with his books and swear by them.
If you have a question about a specific position, you could post a photo or (better yet) post a diagram with the layout. Lots of AzBers would be glad to chime in with advice if you post a specific layout. There can be many subtleties even for a "simple" layout.
http://forums.azbilliards.com/showthread.php?t=64559
In some cases you have several choices in moving from one ball to another. If you're on an unfamiliar table, or (maybe) shooting with an unfamiliar cue, what are you most comfortable executing? One exercise I like to try--though not too often--is switching cues while working through a drill. If I tend to make a shot with inside English only when using my own cue, for example, I wonder whether it's such a great idea to use inside on that shot.
To summarize I'd recommend the following:
1. Buy a good used copy of one of the all-in-one instructional books by Givens, Byrne, Fels, or Capelle.
2. Buy Joe Tucker's
Guaranteed Improvement.
3. Get lessons. Do whatever the instructor tells you.
4. Consume all the free info you can, including videos and articles by Dr. Dave, Bob Jewett, Blackjack, and others.
5. Play some straight pool, one pocket, banks, cowboy, and other games. These games help emphasize skills that are handy in more common games such as 8-ball and 9-ball.