Things to Watch for

Very specfic things, readily added to notes, with specific reactions.

aggressiveness
blind defense
starting hands
Reaction when AK misses
Do tiny nl bets mean weakness, or tease?
Do they bet out with 2nd or 3rd p?
Do they check behind when appropriate on river, or keep blasting?

Do they keep calling flop thin, then folding turn? They do this when runner-runner draw doesn't develop, or over cards don't hit.

Do they raise for free card? If so, you are more likely to rrr

Do they bluff out, then shut down completely if they are called? If so, raise his bets liberally. If he calls or reraises, he's got it.

Are they capable of taking a free card in position, or are they compelled to bet?

Do they raise BB light? If so, tighten up your SB range.

Do they use autofold in sb in nl? If so, you can sometimes fold them for the minimum bet.

NL preflop bets, are they inversely related? Bigger hands, smaller bets?

Does the size of a nl bet correspond to a type of hand?

If they are really quick to release hands, then you can steal with low bluffs. When you occasionally run up against a good hand, you don't lose so much.

Do they make desperate donk bets when they are weak? These will keep you from losing some big pots. I watched a guy with bottom p 5, p77, keep donking. It was a scary board that I'd fold to any but known idiots. I had top pair T on coordinated board, then a K fell. Turned losing session into winning on those two hands.

Do they make stone cold bluffs, immediately folding to a reraise? Good to know you might fold them with a rereraise. Or, do raises mean they have either a legitimate hand or a semi-bluff, either of which case they are not folding.

Do they check behind on the river or bluff, when they miss a draw? If you've been blasting, you might keep it up.

With weak top p, do they call down, or raise? If they call down, you know not to bluff 2nd p or a draw.

Are they provoked by raises? Insecure personality types must not show weakness. Raises actually mean, "you're not scaring me off," not "I have aces."

Do they see a checked flop after your pfr as a trap or weakness? (As indicated by whether bet out or rein in on the turn). If they are a little more experienced, and therefore suspicious, they'll see it as slow playing. So if you pfr, then miss but with a scary flop, you check. If they check behind, you bet turn. Works great.

Do they raise for free cards? If so, your strong non-nut hands should probably be rereraised.

Do they cling to low pocket pairs? If so, you might bet on end, where with others you check for fear of slow play.

Long delay online. Sometimes it means a monster. Other times that they have connection or multitable issues. If you've noticed who is slow, you don't have to fear a monster so much.

When they get top p, do they rr or slow play? Some will slowplay even nines.

Are they either ABC or ABZ?

Do they bet or check top pair?

Do they like suited crap?  If so, rainbow flops are bluffing territory.

Do they avoid river check-raises?

Do they automatically bet when their hand improves?

Good bluffing flop:  k 7 3 – one scare card, but not two, which is more likely to hit someone.
            Bluff MUCH less vs. coordinated flops