Playing the Turn
In No Limit Hold`em, your hand strategy is set up by how you play pre-flop and post-flop. The turn is where this strategy can inform a decision that could potentially cost all of your chips, or double them.

If you have bet a big pair or over pair on the flop, and a card does not come on the turn that is likely to give your opponent a straight or a flush, you should probably continue to bet. If there is a straight or flush draw on the board, someone with a higher pair, two pair, or a set will probably pick this time to re-raise, and you will have to seriously consider releasing your hand. If you have a set, a monster pocket pair or two pair and there is a flush or straight draw on the board, this may be a good time to put your opponent to a decision for all of his chips. At this point there is usually enough money in the pot to justify forcing all of your opponents out, and you still want to make sure you are making it mathematically incorrect for drawing hands to call you.

If you are the one drawing to the straight or flush, you need to consider whether the pot is laying you the right odds to call a big bet after the turn. Your chance to hit both of these hands is a little worse than four to one (assuming the straight is open ended or a double gut shot), so there needs to be more than four times the amount of money in the pot than the bet you are facing for this call to be correct. You can add in the additional money you can expect to win on the river if you make your straight or flush, but only if you can realistically expect this is the kind of player who will have to keep you honest and pay to see that you made it.

You can also use a bet on the turn as an opportunity to semi-bluff if you have a big draw. If the odds of you getting your opponent to lay down (something you have to estimate) combined with the odds of you hitting your big hand are favorable enough, this might be a good time to move all-in. You usually must be sure that your opponent has a decent chance to lay down his hand to you if you try this maneuver. One thing you need to be wary of is the possibility that someone in the hand is drawing to a higher straight or flush than you. This can be dangerous as if you semi-bluff and are called by one of these players, you may be drawing dead. You must use the knowledge you have gained from observing these players up until this point to determine whether a semi-bluff has a chance of being successful.

How you play on the turn is largely a function of how you played on the flop and what you have observed your opponents doing in prior hands. If you try to think ahead frequently, your turn decisions will become much easier.
oOo