Michael Yardley said it best:
"Nothing in shooting is written in stone; ultimately, what is right is what works for you."
Of course, we all have to start somewhere, so a great many books have been written with the intent of telling the novice how to shoot. Michael's book (from Safari Press) is one of the best of them. It is full of excellent advice and practical tips, and should be in every clay target shooter's library.
However - before you go too far down the path of obtaining advice, be it books or coaching - Bill strongly urges you to locate a copy of
The Shotgun Book
by Jack O'Conner
which was published years ago (1965) by Knopf. Your public library may have it, and used copies can often be found on eBay. The 22nd chapter (titled "The Elements of Shotgun Shooting") is what you want to read. Once you have done so, follow up on this solid base by reading chapters 23 ("To Lead or Not to Lead") and 24 ("It's The Angles") as well. The truths contained in these 30-odd pages will help you to pick out the wheat from the chaff as you navigate a field of literature heavily laden with "bum dope".
Now, here's another small tip from Bill, which has nothing to do with books: powerful forearms are an asset to the shot gunner. If your upper body strength is lacking, do start regular exercise - a few push ups each morning when you wake, followed by several arm curls with a light dumbbell (say 15 pounds) may work wonders.
Bill wishes you good luck, and good shooting!