Playing Top Pair
A situation that can be profitable but dangerous in No Limit Hold`em is when you flop top pair. For example, you have AT and the board comes T, 8, 3, or you have QJ and the board is Q, 9, 5. The reason these hands can be profitable is that they are often the best hand on the flop. The reason they are dangerous is that there are many hands out there that can improve to beat you on later streets (community cards).

When you flop top pair, it is important to bet to try to thin the field. You don't want opponents hanging around with middle pair and catching two pair, or landing a flush or a straight, or even pairing a higher poker card than your pair on the turn or river. How much you bet will usually depend on how good your kicker (the side card that goes with your paired card) is and what hands you are likely to be facing. If your kicker is weak, you don't want to bet too much, as you may be in trouble if someone with the same top pair but a higher kicker bets after you. At the same time, if there are flush or straight draws out there, you want to bet enough to make it just mathematically incorrect for them to call.

If you bet and are called, and your pair still looks to be the best on the turn, you should continue to bet it. If you are suddenly re-raised, you need to consider whether your opponent might have been slow playing a set, have hit two pair, or have you out kicked. If you are called and a straight or a flush card comes, you are in a difficult situation. If you don't put some kind of probing bet out there, savvy opponents will bet and take the pot away from you whether they have it or not. If you are against one opponent who you don't know to play too many suited cards, it's okay to continue betting. If you are against multiple opponents, or opponents who have shown propensity to chase draws, you might want to shut down. As with all forms of Hold`em, and poker in general, paying careful attention to how your opponents have played in prior hands and how they act depending on whether they are strong or weak can pay great dividends. Knowing your opponents is as important as understanding any fundamentals of the game, especially in a No Limit situation, where a player can put you on a decision for all your chips at any time.

Remember that in the end, your top pair is still only one pair. By the time five cards come out, if you haven't chased away most of your opponents, there is a more than fair shot that someone has you beat. You should bet when you think you have the best of it, but if you are facing tremendous resistance, you should not be afraid to let it go and wait for a more profitable situation down the road.
oOo