Position, opponent reading and startinghands are what the game is all about.
Startinghands:
It depends on position, action before you, how loose or tight the table is and so on. Just like in texas hold'em. All the good startinghands contain 4 broadway cards. Pairs, suited aces, kings and queens add value to the strength of your hand. Suited middle connectors can be played from late position, but they are somewhat difficult to play. And just like texas hold'em, play tight. AA78 not suited might look good, but it should be tossed away alot of the times you see it. It shouldn't be to fifficult to find a starting hands guide out there, if you want to have something more solid to go for.
Postflop:
Don't chase anything but nutdraws. Chasing a queen high flush, only to find out somebody was chasing the acehigh flush draw, when calling a huge bet on the river is bad. The same goes for chasing anything if the board has paired. You should also avoid chasing strights when there's a flush draw out there. It only leads to headache when an opponent hits the flush on the river. Don't slowplay hands unless you have a hammerlock on it, cause there will be enough "suckouts" even if you play every hand fast.
Last, and the reason I don't play PLO cash games... It is sometimes correct to lay down your hand when you flopped the nuts, and there's no way I'm going to do that. If for instance you flop a broadway straight with no redraws, and you are faced with a good amount of aggresion, laying down your hand would often be the best decision, because you're likely to be up against a broadway with redraws. Anyway you're at best going for a split pot, and there's not much profit in that.