I've played a lot of card games in my life—perhaps inordinately many for somebody with so much else to do. I was sitting around playing funsies poker in the intermediate room on Yahoo tonight, and was reminded of an old adage we used to use playing Bridge. I pass it on, as it may be useful to you...
The longer you have to think about it, the more likely the correct action is to stop.
This is interesting to me partly because it isn't true for computer players. Computer players are unfailing, unflinching realists: neither optimists nor pessimists. If a computer player is sitting and thinking, it means that it is trying to untangle some complex mess in a situation that is marginal. A machine is as likely to unhesitatingly fold as it is to unhesitatingly go "all in". In a marginal situation, the computer can consider a lot of factors very quickly, and is likely to make a decision that is at least clear-headed.
The rule does seem to work well for most humans, though. Human players are almost invariably optimists. They can look at the most marginal kind of garbage and say "but I could get lucky if..." The "if" is generally something really unlikely, and the payoff is really unlikely to be large, but stil... Further, if the situation is genuinely complicated, a human is likely to screw up the reasoning. This could go either way, but in most games mistakes of commission are punished much worse than mistakes of omission. There's always next hand. So by only bidding where you are sure a bid is justified, you tend to slightly underplay, but that's more than compensated by the lack of disastrous overplays.
Actually, the rule is even more true in Poker than it is in Bridge. In Bridge, there are situations where it may be worth overplaying a bit for some reason. In Poker, you almost always want to be out unless you think you're clearly ahead. This is especially true for games like Texas Hold'Em that have no ante. Without an ante, the only way to lose is to do it deliberately, by putting your money out there in a bad spot.
I'm in the middle of reading Matt Matros's The Making Of A Poker Player, a book that I got on Amazon as a freebie with my recent order of Sundown Towns. (Why didn't I get my book locally, at Borders" or Powell's? Because it was unavailable at the former and inordinately expensive at the latter. Oh well.) Matros's book emphasizes the conservatism lesson intensively, so perhaps that's why it was at the front of my mind tonight. So far, there's little in the Matros book I didn't already know, but his style is engaging and he does a good job of pitching his book at amateurs like myself. One new thing I learned, for which I commend Matros highly, is a heuristic for estimating your odds of hitting on the draw from your number of "outs": multiply the outs by 4 on the turn or by 2.2 on the river to get a fairly accurate percentage. I like heuristic rules like this, as they bring the game out of the realm of machines and back into the realm of people.
I won about 400 "dollars" at Yahoo poker tonight, on an initial stake of 1400, in about 3 hours of play. (Of course, I was doing other things the whole time as well. All that folding doesn't take much effort. I put some headphones on and listened for the bell that told me it was time to fold again.) I'll keep studying and learning. After all, I'm a college professor, so I'll have to pay for my retirement somehow.