Tells in Texas Hold'em
Texas Hold'em is as much a game of psychology and bluffing as it is a game of cards and mathematics. A truly good player will be able to play his opponent and will do so to a greater extent than he plays his own card. It is a game where you always want to to appear to be something else than what you really are. If you are strong you want to appear weak, if you are weak you want to appear strong. After all, if an opponent think you have the nuts when you have nothing at all you will win, and if the opponent thinks you are weak when you got the nuts you will get a nice payday while you might get next to nothing if the opponent reads you correctly and understands that you have the nuts. For this reason, you want to deceive the opponent while at the same time see through their bluffs and double bluffs. One way to do this is to read what is commonly referred to as tells. Tells are involuntarily displayed signs that reveals what a player really has. This can range from sweating or not breathing when bluffing, to changing betting patterns when one have strong cards. Tells differs from player to player and can also change as the player ages. It is also important to remember that other players at your table can be faking tells to try to get you to act in the way they would like to see you act.
To learn which tells that are genuine and which one that are faked you should always keep an eye on all players involved in an hand and notice how they act. This is true even when you are not a part of the hand. Keenly observing your opponents will allow you to learn as much as possible about their tells and might allow you to not just spot tells put also to spot the fake tells they use. A faked tell is of course excellent information for you, since it is a tell to the opposite of what they are trying to convey. In other words, the faked tells become tells when you know they are fake.
If you want to learn more about spotting tells you can read a few books on the topic, but in the end there is no substituting experience and the best way to get good at spotting tells is to spend a lot of time at poker tables. You can do this either by playing poker or by getting a job as a poker dealer. Being a dealer will allow you to see a very large amount of hands without having to risk your own money playing.
If you play poker online you are not able to see your opponents which means that you can not use body language and ticks as tells. This does however not mean that there are no tells in online poker - there are actually plenty of tells to observe when playing online. They are however less reliable as they are easier to fake, at least the ones that are based on betting patterns. If you want to spot tells online you need to learn how your opponent usually acts and analyze what information that can give you. Do they bet quickly when they have good cards or perhaps when they want to mask poor cards? Do they check raise monster hand? How much do they usually bet on different types of hands? These are just a few of the many questions you need to find the answers to. When put together it will help you predict what cards your opponent has, but be aware that a skilled online player will know how to fake all this. The best way to get good at spotting online tells is by gaining experience, just as it was with regular tells.