I look for them glancing at their chips when they want to bet. I know a few of my friends that do that and one of them that continues to do it even though he knows its a tell (he isn't trying to fool me, he actually can't help it). A lot of the general things from caro are true such as playing with chips to prevent you from betting and such. My friend also spotted the "look away" after someone checked his cards to know he had a strong hand.

I've been watching the hands of my opponent on the right and left as they bet. I've been able to pick up some tells from their hands as to when they bluff or are actually have a hand. Dan Harrington talks about it in his book.