Omaha is played very much like Texas Hold'em with the exception that every player is dealt four cards prior to the flop and each player must use two cards from his or her hand. Omaha is mostly a game of draws and you may hold the nuts on one street, but you may wind up with the worst hand by the end of the hand. Omaha is very action filled and you must understand the odds to quickly analyze each hand while being in the moment.
In Omaha, you have multiple combinations of possible hands. For example: If you hold AdAc3c10h, it is like you have six possible Texas Hold 'em hands. AdAc + Ad3c + Ad10h + Ac3c + Ac10h + 3c10h. You must remember when you play Omaha that your opponents also have the same number of combinations that you have. Thus, with this hand on a board of 3d3h6c6h8h, you may have flopped trip threes, but your opponent may have caught up by hitting trip sixes or even a heart flush.
Use two cards
One of the biggest mistakes that a new player will make in Omaha is that they will forget that you must use two cards. In Omaha, you also may not play the board. For example: If you hold Kh3d4dJh on a board of KdKc6h6cAd, the best five card hand that you can play is KhKdKcAdJh. You would have to play the KhJh from your hand. However, if the board is KdKc6h3hAd, you may play the Kh3d for a hand of KhKdKc3d3h.