It's a lot tougher when you're playing live. At a casino, you don't really get to choose which table you're at. You just put your name on the list and get the first seat that opens up. After about a half-hour to an hour, you should be able to figure out if the table is good or not. If the table is too tough, you can ask for a table change. Then you'll just get the first open seat at a different table.
You'll have to rely on your memory, notes, and powers of perception to recognize the sharks that you should avoid. And since you won't have a computer that can lable someone as a fish, you'll have to use clues to make educated guesses. Have they rebought a few times? Are they drinking? Did you just see them call two raises with 92o?