Probably the oldest first, shaking hands. I've seen it too many times. It usually denotes a monster hand.
Timing tells, they take too long to make a decision after you've made the bet, if I don't have the best hand it means they most likely do.
Making a huge opening bet, if we are all still deep stacked, it's almost always AK or a small pocket pair.
Limping preflop then going all in if someone raises it, aces soo many times with the same people, they actually get callers, which always surprises me.
These are my local games, so results may vary.