As jacki mentioned in above post spot on ^
Things I look for would be reasons they call a flop and reasons they re-raise a flop - bluff nuts or draw.
great example here : I had pocket jacks in a live tournament this week just before the break and I was short stacked one caller to my raise
the flop came 9-9-10
I bet the flop and he re-raised me, I knew there was no way he was bluffing
because he had only re-raised the flop once all night previously, and his calling range fits his position.
I folded jacks and he showed 9-7s
I went on to win the tournament many players would of pushed all in