i take notes on preflop tendencies by position. things like limp/3-betting, limp/folding, 3b/folding, 4b/folding, any hand i see them get it in with preflop.

also, postflop stuff like if i see them double or triple barrel bluff. how they play draws/whether they semi-bluff flops etc. whether or not they float flops or not. whether they ever C/R bluff. that kind of shit.

also, i will note whether they seem to be able to handread, whether they seem to adjust or be a robot, and what they are likely to think of me based on what they've seen me showdown/do while i've been sitting with them.