I play a few online Poker Tourneys, mostly on Full Tilt Poker, of which I am an affiliate (see my FTC page for disclosures).
The poker game I play the most is texas holdem – and it is quite a challenge. While cards matter some, it also helps to know your opponent’s tendencies.
Does he open light for a raise (starting with a weak hand such as KJ versus a pocket pair or AK). Does he re-raise light. There is a lot that goes on in a no limit holdem game and to succeed,you need to keep your wits about you.
It is a good idea to keep notes, but also be aware that an opponent might play differently from one day to the next or even from one hand to the next.
Do you take notes? Does it help your game?