[Harv72b]

Everyone who plays poker falls into one of two categories: loose, or tight. And everyone who plays poker falls into another one of two categories: passive, or aggressive. Don't concern yourself with "neutral".

So the first thing you want to look at is whether a player is loose or tight. Generally speaking, if he's seeing more than 25% of the flops (including times he posts the blind), he's loose. In a typical B&M small stakes game, most of your opponents will be loose.

Now look at how often he bets or raises vs. how often he calls. If he calls more often than betting (or raising), he's passive. If he likes to take the lead & push his made hands, he's aggressive. We're not talking about when he's holding the nuts or something close to it; rather, things like betting or raising with "just" top pair.

Once you've classified an opponent as tight/passive, tight/aggressive, loose/passive, or loose/aggressive, then you can start looking for more detailed information. Things like raising on a draw, check/raising the field, playing position well (or not), etc. The players on either extreme (calling stations, maniacs, rocks, etc) are generally so obvious in their behavior that it shouldn't take you more than an orbit or two to identify them.