Do not sit down for the first one, reconsider several tables to find one.
Do not play with strong players, look for players to weaken themselves. At the tables there must be at least 1-2 players, whose weak spots you can see.
Do not sit at a table in front of a player with a large stack, usually he will act after you, and a larger stack gives him a lot of looseness, and he will not be afraid of you. You will see that very often the place is released just before such players, you know? Even worse, if there are a lot of big stacks at the table (they won them including those who freed you, you do not want to be the next). Look for a comfortable game for yourself, do not be lazy to get up and leave, usually if the table is bad for you, it's better it will not.
Do not play if the player after you is too aggressive and often you rearrange, forcing to make unpleasant decisions (the level of pre-flop aggression will show you the program).
Make notes on players (notes), probably will still play with them, notice their weaknesses, the manner of the game, what it is capable of and with which cards.