Poker Tells are overrated. Let's just start out with that. Many people who don't' know much about poker assume its 90% figuring out what your opponents has by looking at him. They think its all about bluffing and reading opponents tells. The truth is, poker tells are important, but you can win at most games without ever getting a poker tell. Poker tells need to be just a secondary source to sound fundamental poker.

Here are 10 poker 'tells' that you can look for when playing poker:

1. Watch the Eyes
   This is why many pros wear sunglasses or visors/caps when playing, they know that the eyes rarely lie. For example, many players can't help but stare at big hole cards, so their length of time peeking is longer. Conversely, if a player is looking to steal the pot, he may look to his left to see if the remaining players, who haven't yet acted, have quickly glanced at their cards and are likely to fold. Another example, a player may try to ask you questions about your hand, knowing that people rarely can "look someone straight in the eyes" while being dishonest.
2. Facial Expression
   Again, many pros try to disguise their entire face by wearing a cap and looking downward. This is to avoid the classic stare-down that poker pros are famous for. They may try to study your face for nervousness (detecting a weak hand), or even look for repetitive characteristics like a body "tic". You may have obvious unhappiness in your face when your hand is weak, and conversely, you may show a contrasting show of confidence when your hand is strong.
3. Weak is Strong/Strong is Weak
   In its most simplistic form, this usually applies to novice players but frequently applies to pros as well. Basically, players like to be actors, and when they have a monster hand they tend to look disinterested. For example: "Oh, is it my turn to act" or "Oh I guess I will play these cards". Alternatively, a player increasing the level of his voice while raising the pot, and trying to look intimidating.. may be running a bluff.
4. Anxiety
   Anxiety typically occurs in people when they are confronted, or anticipating confrontation. Psychologists call this the "Fight or Flight" stimulus response, which links back to the days when we were cavemen/cavewomen. Physical changes happen including flexing of muscles, eye pupil dilation, palpitating heart rate, dry throat. In poker, when someone has a big hand they are typically ready for confrontation and can exhibit some of these characteristics. You may see the chest expanding abnormally, or you may notice the players voice become slightly higher as he makes a comment. Some of the top players in the game will stare at the vein on the top-side of your face for blood pressure changes. During a bluff, the player may demonstrate anxiety, but if he knows he will fold the hand if re-raised (non-confrontational end) may look quite comfortable.
5. Trembling Hands
   Also, a byproduct of anxiety, beware of a player whose hands are shaking, this nervousness can represent a big hand.
6. Glance at Chips
   Again, relating to the eyes. It is common for players to quickly glance at their chips if they connect with the board after a Flop. This may be a subconscious reaction, but the player is already planning his attack.
7. Peeking Hole Cards on Flop
   Some players will take another look at their hole cards when, for example, the board is showing a potential 3 card flush draw. Typically, the player is looking to see if one of his cards is connecting, because he remembers only that the two cards are different suits.
8. Repetitive Betting Patterns
   Usually the most revealing tells are based on the way a player habitually bets during particular situations. For example, maybe the player always checks when he has made the nuts, or a player may regularly fold after being re-raised.
9. Body Posture/Attitude
   Some players show obvious changes in their posture based on their attitude/hand strength. For instance, you may notice their shoulders drop/slump when they are not confident (weak hand). Conversely, you may notice the player is very attentive and sitting in an erect position when he has strength. You may also notice that a player who bluffs a lot, leans forward in a confrontational way... remember Strong is Weak!
10. Chip Stacking
    When you first sit down at a table, study the way the players stack their chips. Although it is a generalization, loose aggressive players typically maintain unorganized/sloppy stacks, while tight conservative players keep well organized/neat stacks.
    In the popular poker movie 'rounders', Mike picks up Teddy's 'poker tell'.