CHECK- When there is no bet yet and you decide not to bet because:

Slowplaying is a good technique for getting more money into the pot. If you are holding the best hand and have a feeling that people will fold if you bet, then slowplaying is a good choice to keep people betting. By checking the best hand, you allow your opponents to add money into the pot either on a bluff or with the second best hand. When they bet, you come over the top of them and it can drive them nuts, making you a lot of money.

If you have identified an aggressive player at the table, the slowplay is a great move to make more money off of their aggressive play. The aggressive player will try and bluff at a lot pots trying to steal them. When you check the pot, they will try and steal the pot, but if you slowplay your hand you can really put them in their place on this hand and in future hands. By raising the pot after they bet, you are showing that you recognize their aggressive style of play and know that they are bluffing a lot of hands.

Just like with bluffing and semi-bluffing, do not become predictable with the slowplay. It is a great strategy to use, but when used too much it becomes obvious. Remember, deception is key at the poker table and using a technique too much will lose some deception.

WARNING: Slowplaying can be an extremely dangerous and costly move if not used properly. If you decide to check a strong hand and nobody bets after you, then you don't have the opportunity to slow play the hand. Instead, you have given your opponents a free card. Free cards are not good to give away, especially when you are holding the best hand. Free cards will often fill in flushes and straights, making your hand second best, and ultimately a loser. Slowplaying is best when the flop is of three different suits and the cards are spread far apart. This leaves the chances of a flush or straight draw low, making the slowplay a good move.