After various ups and downs over the last few months at different levels, I thought I'd share my provisional conclusions:
First, where I've typically gotten into trouble is with loose plays. Ok, I've also WON my fair share with these, but I'm not convinced that, when you add up all the variation associated with them, one gets even a break-even total. I think they have their place only when the table is pretty tight (few players seeing the flop) and when other players in the hand think of you as more or less a nut-peddler. THEN (and really only then) it's a good idea to turn up the juice.
Where I've had very good luck is with very tight play, really looking mainly at how boards are likely to develop on various hands--including sets on draw-heavy boards; betting and raising with good draws, and only with fairly serious draws, just folding away 9-outers and such unless pot odds give me a reason to do otherwise; also, not messing very much with top 2 unless the board is such that the hand can continue to improve--e.g.: pot-sized bet to me in LP in a multi-way pot with AQ98 on a 2-tone board of AQ3 where I don't have even runner-runner flush draw, I just fold and move on. I have lost nothing but my limp here. I really think that calling with position here becoms viable only if you have a good grasp of your opponent and are going to be able to rep with position hands that you don't have but which scare your opponent. If that's not the case, I've had better luck with just forgetting about hands like this as long as the table is likely to give you action on some big hands.
So, my conclusion is really this: At tables with lots of loose money, don't worry much about folding possible "best hands" as long as you can do this before being in very deep. Just move the chips in when the board is likely to develop in your favor. Really as simple as that.