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Tells
Hesitation, then check	This is one of the biggest tells out there.  Most of the novices out there don't realize that when they hesitate before making a call, they are putting a big sign on their forehead which says, "I have a weak hand".  An extended pause, then a "check" is almost always a reason to bet.  More so if the hesitation is on the river.
Hesitation, then Bet	An extended hesitation and then a bet respresents a strong hand.  The player is thinking how to extract the most money from you, thus the long pause.
Limper, then big bet	A player who limps into the pot in position, then bets big on the flop usually represents a big hand...most likely a big pair (Aces or Kings).  He wants to trap,then fears someone drawing on him on the turn, thus the limp and the big bet.
Slaps their hand down hard and checks fast	This is almost always a sign that the player has hit a big hand and is looking to check raise.  Don't fall into the trap.  Remember, a player acting weak usually means that they have a strong hand, and acting strong, means that the player is weak.

Top five MISTAKES in low limit hold'em

Call with AJo in the small blind in a raised pot.  It's not worth it. You'll be out of position and even if an Ace flops, you may still be beat by an AQ or AK.  Unless you are playing at a very very loose table, it's better to stay away from this hand. Limp in with a small pair (less than 8-8) from early position.  Again, it's not worth the money.  The pot could be raised in middle/late position and you'll end up putting two bets out drawing to two cards to make your set.  Not worth the money. Plays mediocre hands like Q9, K7, K8, K9, J8, etc. in any position, except of course it's a free hand.  If you do happen to play them, you should be in late position without any callers and make it a raise instead of a call.  I would only advise making this play once in a while because these hands are usually dominated post flop. Play middle or low pair after the flop, unless you are getting at least 5 to 1 odds on your money.  So, if you have 7-8 and the flop is 8-T-A, I wouldn't play for one more card unless there's at least 5 small bets in the pot before you call.  Definitely don't play it if you think there may be a raise or if there already is one. Fold to a bet on the river if you have at least A high and there's more than 7 or 8 times the big blind in the pot.  First off, if you are going to play to the river, then you shouldn't fold to one bet with so much money in the pot.  All you have to do is win once out of 8 times and your getting even money on your call.  If you're going to fold, then you probably should've folded earlier.