lol it is confusing with all the 4s and 2s above But really it's very simple if you know Holdem, if you play, just play it the same as Holdem that's all but remember you can only use 2 out of your 4 hole cards, otherwise the rest is the same.
A classic example tonight of how it usually goes wrong though - I had something like QQT5 as my hole cards, then the flop came down QT3 (I can't remember exactly, something like that though). So initially/briefly when you look at that flop you think 'wehey, full house!' but actually it's not a full house at all, it's only 3 Queens with a Ten high kicker (because you can only use 2 of your hole cards, so QQ would be used and the T3 would be discarded, leaving you with just QQQ+T kicker).
I think that hand I probably lost to a Queen or King high straight - a lot of the time you end up losing that way if you're used to Holdem but then start playing Omaha - when you think you've got a decent hand after making a set of Queens (3 queens) or w/e, it's not unusual for someone else to trump you with something better - which is mainly a result of the extra permutations that 4 hole cards provide for everyone.
Can also be tricky when the board is paired because despite you making your full house, if you don't have the nut full house (ie the highest possible full house combining your 2 hole cards and the 5 board cards) then you're more likely to come up against someone else that does in Omaha compared to Holdem (again because of the 4 hole cards vs 2 in holdem which provides better chances for everyone).