I am just a recreational player but I have a few things I learned that have helped me out. I try to avoid players that have conversations with the dealers, especially about other players. Its obvious they put a lot of time in. I also like what Deceptionist said about recreational players. The ones that keep ordering drinks and not paying real attention to the game. Get position on them. Money flows left. The legs is also good. I like to watch people's eyes and hands as well. Some players are poor enough that they stare down cards that made their hand. If I have a tight player to my left, I like to watch how he holds his cards that he likes vs cards he doesn't.
Stay disciplined and don't look at your cards until its your turn to act, and watch the players when the cards come out on the board. They'll still be there when its your turn to act.