Its little tricky but if you stay tuned your rival movements you finally catch him up, when he is bluffing or he has good hand or even when he plays agressive
You quoted Sun Tzu wrong there. It reads like this:
Know yourself but not your enemy and you will win half the time. Know your enemy and not yourself and you will win half the time. Know neither your enemy nor yourself and you will lose every time. Therefore know yourself and know your enemy to be assured of a victory.
Make notes in software about some players. I have 2 types of notes:
- bleff a lot with weak cards
- do not raise first with super cards
And just observe.