Poker Tells that Say:
I Have a Good Hand
Acting Uninterested in a Hand While Still in It
This is usually a sign of a strong hand. The player is pretending that he's not excited about his cards while he is.
Sighing and Shrugging
If a player makes a show of sighing or shrugging and says things like "Oh, I guess I'll call" or even "Why am I calling?" he probably is overacting and is trying to hide a big hand.
Glancing at Chips after Looking at Hole Card
When a player looks down and sees strong hole or pocket cards, he may glance over at his chips to see just how much he can bet.
If you notice a player's hands are shaking as he places his bet, he probably has gotten a really good hand.
Some players can control the shakes, but it's harder to control the heart-racing that comes when you see pocket aces or hit the flop really hard.
If you can see a player's chest visibly rising and falling, they have an excellent hand!
I have a Weak Hand
Staring Down Other Players
If an opponent is staring you down, he's trying to represent strength. Usually, he has a weak hand.
He might have something, but it's something that can be beaten or drawn out on.
Inexperienced players will often hold their breath if they are bluffing.
I have a Drawing Hand
Checking Their Cards After a Flop
If the flop shows the possibility of giving someone a flush or straight draw, watch for people re-checking their hole cards.
They're checking to see if they have a piece of it, whether that black Ace was a spade or a club.
The player doesn't have the flush or straight at that point, else he wouldn't have to check it.
Taking a Long Time Before Calling a Bet
If a player looks into the pot, he is probably doing some calculating in his head. He's figuring out the pot odds to see if it's worth to try and catch the cards he needs to complete his drawing hand.
A final note: more experienced players may give off false tells, so the first thing to read about other players is if they're novices or pros.