How many
hands they play and how aggressive they play is a good place to start! Also raise sizing!
Eg (and I've seen these) guy raises who usually limps, another guy re raises and then the original person who normally limps re raises again.... they go all in and guy who usually limps has aces which is not a surprise at all! Pattern: sudden strong moves can mean strength!
2 a person barely plays any hands and finally plays one but the flop is low with no face cards so they check it to you and you bet and they fold. Pattern: even though they were the pre flop aggressor they checked on a low board and considering they barely play any hands they must only play face cards ie tight passive
3 person raises normally and you follow them to the flop they normally bet half pot or check but this time on a 789 flop they bet pot! It's possible they're
bluffing but the last couple of times they bluffed they bet half pot, conclusion probably has a straight! Pattern: bet size suddenly changing....
Another thing should do is look on YouTube or google and find out what tight passive, thight aggressive, maniac, nit, loose passive and loose aggressive means in poker or on YouTube type in "poker player types" or something!
This way when you notice something you'll be able to put the behaviour into some sort of category!