Just raise with the absolute premium hands (AA, KK, QQ, AKs, AKo in any position, add AQs, KQs, JJ, TT and maybe AQo and AJs in late position if pot is unraised), and raise big to try and get down to one or two callers.
If they're playing loose/passively, suited connectors (straight/flush value) and low pairs (set value) go way up in worth, so feel free to limp in mid/late position with these if there's not a lot of preflop raising going on, and bet big right away if you hit on the flop (if they're very loose they might call with something that isn't good, and slowplaying gives yourself the chance to be drawn out on later unless you flopped something huge). Don't bet draws unless you have any specific reason to think you're not going to be called. If people are getting crazy with preflop raises as well as playing loose, just wait for one of the aforementioned premium hands until you play back. If you get drawn out on, or if you end up playing card dead for ages... well, it happens I'm afraid.