I'm assuming you're not using a HUD or you're playing on Bovada
? Otherwise let the HUD help inform you of ranges and use the notes to record unusual tendencies.
Things I note when I don't have a HUD: how often they open in early late middle positions. how often they cbet. do they slowplay? if they are a limper, what do they do when raised preflop? leaks/errors in their post flop play such as "overvalues top pair" "bets huge with bluffs".
a typical note when I also have HUD stats might read something like this: "Limpy-cally. overvalues top pair. calls cbets with no pair no draw. tiny min raise on river with nuts. semibluff jam 2x pot on flop. chases with bad odds
. flatted river with 2nd nuts"