Holy crap...there's a lot of bad blackjack advice in this thread.
A decent introductory book -- if you're interested in learning basic strategy, and also interested in why you really don't want to play anything else in the casino except craps -- is Andrew Brisman's American Mensa Guide To Casino Gambling. Despite the name, it's a very readable, thorough look at the math behind the various games, and the best strategies (if any) to employ.
The principle behind basic strategy is that -- in the absence of any other information about the deck -- there is only one correct way to play every situation, based solely on the composition of your hand and the dealer's upcard. If you learn how to count cards, then you can make some different choices and win. If you play by your gut...you might as well give me your money now, since I'll put it to better use than the casinos will.
Is it true that someone else's play affects "your" cards? Well, technically, sure -- the order of the deck is fixed after the shuffle. But since you DON'T KNOW THE ORDER OF THE CARDS, you have to treat every situation as "random," and play according to basic strategy. There is no such thing as a "bad play" by another player -- make your own choices, drink your tasty adult beverage, and shut up. If someone starts harassing you, move on.