How to spot a Poker Tell by Dutch Boyd

I've gotten a lot of emails about poker tells... what are some common ones, how to spot them, etc. Here are some ideas to get you started.
There are some very common poker tells that most new players will exhibit (e.g. shaking hand when they bet means a monster, looking down at their chips immediately after a flop means they connected, etc.). Most of these can be found in a book by Mike Caro called Book of Tells. He basically breaks down tells into two categories : acting tells, where a player acts weak when they are strong (e.g. a sigh when they make a big hand, a "poker-clack" when they bet, a shrug) or strong when they are weak (e.g. staring you down when they're bluffing), and non-acting tells (e.g. the shaking hand, the looking down at chips). The acting ones are tells where people act in a certain way to get you to act the way they want. New players fall victim to these types of tells all the time. The non-acting ones are tells that players are not conscious of.
Basically, Mike Caro's book is a good start, but it's definitely not the end. With tells, what you have to do is get a line on each player. Each player will exhibit different tells. Look for a difference in the way they play two hands... ANY difference. If you spot a difference that is consistent, it's a tell. Player A might sniff a little when he has a big hand, and not sniff when he doesn't. Player B might sniff when he's bluffing, and not sniff when he's strong. Player C might have a vein on his neck that goes CRAZY when he's bluffing. Player D might have a vein that goes crazy when he's NOT bluffing. It's going to be different for each player, but once you spot a difference in the way they play, you've got them. Then you just look to see him turn over a hand. You correlate the strength of what they show to the behavior variance and you've got yourself a tell.
Examples : (1) Sammy is a player at your table. You notice that in some of the hands he's in, he makes his bet with the biggest denomination chips possible. With others, you notice that it's with the smallest demoniation chips. He bets $10k one hand and throws two $5k chips in. He bets $10k another hand throws in 10 $1k chips. He does this a lot, varying the chips he bets. You see him bet 10 $1k chips and fold to a reraise... then you finally see him turn over a hand... he flopped Aces full and bet the $5k chips the whole way. Now you know it correlates to strength... it figures that when he bets smaller denominations, it correlates to weakness. He's yours. (2) Joe is peaking at his hole cards before it's his turn to act. You're clocking him... every time he peeks down, you start counting. Most of the times, he peeks down for six or so seconds, then starts looking at the action. One time, though, he peeks down for 2 seconds, looks straight at the dealer, raises when it's his turn, and turns over aces. He's yours.
Those are just some examples of what to look for. The key is you spot a difference, you correlate it to strength or weakness, then you exploit it. If you spot a tell that means strength, you lay down your Jacks preflop. If you spot a tell that means weakness, you raise with your 82o. Sounds simple, right? It's not... but hopefully this will get you started.