[citanul]

well, you play poker, so does your opponent.

you're going to call on a flush river for a bet of some maximum size x
you're going to fold on a flush river for a bet over that amount x
your opponent is going to have the flush some percentage of the time y
your opponent is going to bet without the flush on the flush river some other percentage z
your opponent is going to bet some non flush card rivers with hands you beat that don't have a flush draw to them some amount of the time a
your opponent is going to bet some non flush card rivers with hands hands that beat you that don't have a flush draw to them some amount of the time b
your opponent is going to bet the non flush card river with flush cards that you beat some amount of time c

then you set up a bit sort of matrix based on how often you think he has each of those things, and seek to win the most / lose the least.

your hand has some value to it, having top pair. seeing a showdown isn't a crime. seeing the showdown and having your opponent be bluffing some good fraction of the time, instead of purely value betting, is very good too.

raising on the turn costs chips. those chips could otherwise be used to call a river bet you might have to call on the end anyway, or they could be chips you're just making yourself fold to a turn reraise. while the percentage of the time your chips goes in and gets called on a turn raise and your hand is good is low, the chance that he bluffs into you on the river is significantly higher.

citanul