Taken form SportsCrewPOKER.com:
Your Opponent:
[size=+1]
PART I[/size]
[size=+1]After You Fold..[/size]
One unique aspect of poker is that you can drop out of a hand, invest no further money in it, but still watch the play in action. This is critical. In poker, you are afforded the opportunity to watch your opponents play their hands. If you're lucky, you get to see their hands and work your way backwards to match what the player was holding with how the player played it. Here are some examples. If you see that one of your opponents was dealt a strong hand right off the bat, but didn't bet it as such, then you know you're either dealing with a passive player or a player that is willing to slowplay the occasional strong hand. If you see that one of your opponent was dealt a mediocre hand and bet it strongly, then you know you're either dealing with an aggressive player or player that is willing to bluff / semi-bluff the occasional mediocre hand.
[size=+1]Over Time[/size]
However, these observations apply to single hands. You'll not likely form strong player profiles from only watching a handful of hands. You need to keep your eyes on the action when you're in the hand and especially when you're not in the hand. Poker rules let you sit and observe your opponents to collect as much pertinent information about them as you can.
In the first example above, if you catch two or three instances of the same player slowplaying decent hands, then you could very well be dealing with a passive player. Watch it, because you don't know what a passive player has. Check with your drawing hands, and bet and raise with your strong hands. He'll stay in against you, but won't make it expensive for you to chase your hands. You've started to develop a strategy in how you will deal with this player. And that strategy was borne of observation.
Be careful with players who are advanced enough to alter their style if they think that you are catching on, or if they think they're being watched. Even the worst players can alter their style, so keep your player profiles flexible enough to adapt. However, in the face of an uncertain decision, it's better to use information you've collected than to base it on no information at all.
[size=+1]In Conclusion[/size]
When Samurais had to undergo meditation training, their masters would walk around the room with canes. If they thought you were sleeping instead of meditating, they would whack you across the head with the cane to wake you up. The point: there is a fine line between meditation and sleeping, just like there is a fine line at the poker table between concentration on observing the action and "zoning out" because you've folded from the hand and couldn't care less who wins the pot.
Keep your eyes on your opponents, and study them at every chance, particularly if you've folded. Build your player profiles, use the profiles to help you make on-the-spot judgments, and adjust your profile as the player surprises you with a move you weren't expecting. It may come down to probabilities (ie. about a third of the time, he's semi-bluffing when he raises). That's fine, too.
[size=+1]PART II[/size]
[size=+1]Bluffing[/size]
Poker is characterized by bluffing. Every move that a poker player makes at the table should have one of two possible meanings: the obvious and the deceptive. When a player bets, is he being aggressive with a strong hand, or is he bluffing with a weak hand? To some, this is the essence of poker. Guidelines on how to deal with bluffing are difficult, because there's nothing cut and dried about it. It varies with each opponent you play against, and it also varies with the table. Some games just don't have a high volume of bluffing (which I would say signals an opportunity to introduce them to it). We'll focus on three guidelines: the type of game, the mathematical aspect, and the psychological aspect.
[size=+1]Type of Game[/size]
Some games just don't have bluffing. It may be that the game is too friendly or too loose. If the game is friendly, you may not suspect that much bluffing is going on. In this case, considerably drop the probability that you're being bluffed. If you're up against a big bet, consider that it's likely a strong hand. If the game is loose, then don't even try bluffing, it's a waste of your time. If you can't fold everybody, then the bluff fails and you've lost your money. Bluffing only works in games tight enough that a bet could potentially fold the other players.
[size=+1]Mathematics[/size]
In our last article, we talked about building player profiles. If you've included probability in your profile, then mathematics is important (ie. that player is bluffing roughly 10% of the time). It works like this. When you're asked to call a bet that may potentially be a bluff, compare the size of the bet with the size of the pot that you are playing for. If the bet is $1 and there is $20 in the pot, that's a 20:1 payoff. Now, compare that payoff to the probability that the player is bluffing. If you believe there is a 1:10 chance that the player is bluffing, then you would be correct to throw $1 in a pot as small as $10 and certainly one that is as big as $20.
Don't feel like doing math at the table? That's fine, just remember this guideline: don't allow yourself to be bluffed out of a big pot. If the pot is big, consider calling the bet even if your opponent may have a strong hand. You don't want to miss a big payoff because you were bluffed out of the pot.
[size=+1]Psychology[/size]
This is the most important one of all. Bluffing is psychological. The player is effectively "lying" about his hand, and the question is whether or not you believe it (with money on the line). There is no simple advice for this. Players with better instinct are less likely to be bluffed out of a pot. They will either 'sniff' it off their opponent or sense it from their opponent's playing style. The most relevant advice here stems from our last article on building player profiles. If you've never seen a player bluff, then you have no reason to suspect that he would. But, he might be. And, if you fold, you may never find out. Only instinct can detect bluffing, and only experience can build instinct. Follow the letter of my last article on studying your opponents, and over time, you should develop some instinct. If you can do it cheaply, one way to respond to a potential bluff is to re-raise. This will typically fold a bluffer. If he calls your bet or raises back, suspect that he may have ahand.
[size=+1]In Conclusion[/size]
Don't sit down at the table without a gameplan of how you intend to play. Mind your level of intoxication based on how seriously you take the game. Study your opponents at every chance and develop mental player profiles as you go. Finally, know when to call, fold, or raise a bluff. Master these four concepts and give your opponents a better run for their money