Most poker books advise,* as rule number 1, to start by picking a good table. The 10th best player in the world will suck at a table against the best 9. The 10th worst player in the room will bake big money against the worst 9. Pick a table with bad players. Avoid tables with thoughtful, smart players.
You can identify a good table easily: there's a lot of banter back and forth, a couple of friendly drunks, and frequent overly-dramatic congenial outbursts. The last two times I played at tables like this (against a drunk who told us that money didn't matter and against The Walrus), I did really well. The three games after that, the table was almost silent, contemplative, and I did poorly.
Problem is, with a small poker room (Washington state law limits to 15 tables total, including blackjack, etc.), you don't get much choice of which table to sit at.
The problem, therefore, isn't that I'm not following the books' advice -- that's tough to do in this state -- but rather that I'm not adjusting properly to the tighter, smarter tables. This is the exact same problem that I've faced this year in online play. When I have a decent hand (top pair top kicker), I take the perspective that unless someone else is raising, I've got a monster, and the other players in the pot are idiots. The problem with this? Most of the other players aren't idiots any more.
Two illustrative hands which cost me $27 each. I'm in late position raise pre-flop, and get heads up on the flop. Early position checks and calls my bets through the river. I lose:
Example 1: I've got AJ, and the board is AT3/T/8. I lose to TT which hit quads; he was check-calling so not to lose me and hit the $133 quads bonus.
Example 2: I've got A9o, and the board is 945/2/K. I lose to 54.
When my bet gets check-called on the turn, should I be checking the turn? I think so. I've got to stop and ask myself "why are they calling?" And "because they're an idiot" isn't a good answer any more.
A third example with different circumstances: I'm in early position with 33, heads up on the flop, and the board is 449/K/K. I bet the flop, get called, bet the turn, get called, and then without realizing that my hand's been forfeited by the two pair on the board, bet the river, and get beaten by A7o. I'm showing agression, and getting called on the flop, which means he either has a 9 (I'm dead), overcards (I'm about a 70% favorite), or a flush draw (I'm a 60% favorite). It's pretty close to even odds that I'm going down here, so I should slow down. I didn't.
(He won't have a 4 or an overpair, or else he'd have raised.)
Against better-than-mediocre players, I need to play smarter post-flop. If they're raising, they've got a reason. If they're calling, they've often got the right odds to do so.
It cost me $100 over two hours, which is twice as good as I did the last two times (where it cost me $200+ in the same time period). I did win a few hands, and won a partial pot with my ace-high flush against an all-in full house and a two pair). Although I didn't like my play in the examples above, it reinforced my learnings from the home game at OS17: if you play like everyone else at the table is an idiot, you'll learn that there's only one idiot at the table.
* Sklansky's and Carson's Low Limit Hold Em titles, for example.