play tight like Rob said and that involves the following:
don't reraise/raise with aces unless you can get more than half of your stack into the pot preflop. If you can do that I'd take my chances, but not with AA and 2 other hideous cards.
Don't get involved in huge hands with the under fullhouse, you will get in a HUGE amount of trouble doing that, because in omaha its many times when you have to lay down fullhouses, if you don't have the nut full in aggressive betting measures I wouldn't reraise if your want in, I'd just call.
Stay away from calling low pp preflop. If you fall in love with this, it'll be plenty of times where you'll flop a set but someone else will flop the nut set or not even a nut set but a set that out does yours, in this case your basically drawing dead. I wouldn't get into a hand with low pocket pairs unless im double paired in the hole and I'm raising, you don't want to flop a set with the likes of 22-88 because its hard to know when to lay down a set, its definitely easier to know when to lay down a boat than a set by itself in omaha.
Don't draw to nothing but the Nuts, that goes for preflop and postflop. don't call suited hands without the Ace unless you have a nice connecting straight hand. When the flop comes down draw to only the nuts, especially straights. don't draw to an open ended straight when you have the lower end of the straight, if you can't make the nuts most likely you should be folding on the flop.
Don't play less than top 2 pair aggressively on the flop, and there are times when you shoudlnt even play top 2 pair aggressively (there are even times when I would slowdown with sets on the flop with no made straights or flushes showing yet also). In that respect, don't play to make pairs, you should only call draw worthy preflop hands. premium starting hands would be would be stuff like aa kk double suited, 910qj double suited and something like 789A with the ace suited.
don't slow play the flop unless your check-raising big on the flop, or in the rare instance that the flop is hideous, because that don't happen often in omaha, usually someone has outs to some type of serious hand
If a straight shows and you have a set, call if you are getting a good price, you still have outs to make a boat and a lot of times when you hit that boat you can break someone with the straight or the flush that was originally showing.
Obviously reads and certain situations can make you need to act against some of these points, but I think this some things any beginner omaha player should pay attention too. Thats part 1. lol