if an opponent has a full house, he can't have a low. if he has a low, he can't have a full house.
this is such a simple tip that so many people forget.
for example, if your hand is something like 10-9-8-7-6-4-3 (suits irrelevant) and you're heads-up against something like x-x-3-7-7-K-x, you should be capping fearlessly. you are on a freeroll; it is impossible for you to not win at least half the pot.
i was saved a great deal of money in a hand i played at a casino, where i had (A)-(A)-5-5-6-4-(K) against x-x-8-6-2-Q-x, my opponent bet out, i raised feeling that my opponent might have missed the low and rivered a worse two pair, and my opponent just called.
my opponent's hole cards were 9-7-5 for the rivered straight and 8-7-6-5-2 low. he just called thinking he was beat for the low or beat for the high by a boat. thank you fish!
aseem