re: Poker & Betting Sizes
The most effective method of bet sizing is to base it on your knowledge of your opponent`s tendencies and not on your own holding. This is one element of the often-mentioned advice to play the player, not the cards.
For example, if you have a strong hand and anticipate that you will win at showdown, your aim is to build the pot. Therefore, you should bet as large a sum as the opponent will call. If you have been watching him (as you should) you will know whether he is timid and will be likely to fold his non-nut hand to a bet of (say) half the pot or whether he is a calling station and will call a pot-sized bet with anything like a playable hand. You adjust accordingly.
In the opposite situation, where your hand is vulnerable and your aim is to take the pot down at once, you must bet sufficient that your opponent will not call without a monster. It is especially critical to get this right. Bet too low and the opponent will call with a wide range of hands and may suck out. Too high and you will lose heavily on those hands when the opponent does indeed have the strong hand with which to call.
To see this in action, play in (or just observe, if you prefer) a CC buyin game. Watch the experienced tournament players such as Irexes, KatyMaty, Alien Genius, or that toasty fellow. See how their bet sizes change as the blinds rise and as the table situation changes. For example, note how Alien Genius sometimes targets a weak player in the big blind and uses his table image to steal the blinds with a min-raise.