Poker, just like when playing in person, also has tells in the virtual world. Poker players begin to fall into the rhythm of the game and their subconscious actions provide clues as to their strengths and weaknesses. Some of your opponents' purposeful actions can give also you clues.
The bets go around the table, each player takes a moment and calls, but one player's call action moves much more quickly than everyone else's. You recognize this because you use it yourself from time to time; it's the website's auto call feature at work. You can see how this option comes into use. If you have a strong hand, you know that no matter what anyone bets, you will call. Instead of waiting to play in turn, you click the auto call button. The use of the auto feature does nothing but give away information about your hand. Watch for the use of this feature but don't use it yourself. How much time do your really save by using it, anyway?
Betting at the Button
Everyone checks around the table. The last person (the person on the button) places a bet. Is this bet due to a strong hand? It's more likely that this person is taking advantage of the knowledge they obtained with everyone else's check. It seems logical; if everyone is being passive why not bet to cut some of the competition? Don't assume strength if the person on the button places a bet after everyone else calls.
Never take anyone's poker identity at face value. Just because someone's identity is Mrs. Jones, and the avatar is an elderly woman, don't assume that this is an accurate depiction of your opponent. If the identity is poker loser, don't assume this player is unsuccessful at poker. People can portray themselves any way they wish in the anonymous online world. Identities are deceptive and no knowledge can be taken from them.
Some players like to chat it up and discuss random subjects to make the game feel more personal. Others use the chat to mislead. A perfect example of this is a bluffer who is about to get caught and folds his hand before the showdown. He then states, "Oops I accidentally pressed fold". Oh, really? Those who chat about their strategy, the cards they are holding and like subjects are usually telling lies.
Note: Tells are great to pick up on, but always be aware of the possibility that people purposefully creating the illusion of a tell. Keep this in mind when looking for tells when playing online poker.