There are two versions of Omaha. Omaha High only and Omaha High-Low Eight or Better which is a game where the high hand and low hand splits the pot.
You may hear the split game called Hi-Lo, Omaha
In order to have a hand qualify as low there must be no cards higher than 8 in your five card hand. An ace can be used as either high or low. A flush or straight is ignored when making a low hand. Therefore the lowest hand is A 2 3 4 5. This hand is also called a “wheel. Since in Omaha you must use two cards from your hand, there must be three cards on the board that are eight or lower. If there is no qualifying low hand, the winner with the highest hand will win the whole pot.
Many players look at their starting four cards and if they see an A-2 they act as if they have just found the Holy Grail. They immediately raise with this hand which is wrong for several reasons. First, is the fact that in order to qualify for low there must be three more low cards on the board. This is not always the case and if three high cards come on the flop, you are in big trouble. Another reason not to raise pre-flop with just A-2 is that if an ace or a deuce shows up on the board you hand will be counterfeited as you no longer can use your A or 2 unless a fourth low card shows p on the board by the river.
The final reason to consider when you raise with A-2 is the fact that every other player with A-2 will also be in the hand. If you do make your low instead of getting half the pot, you will get half of the low pot which is a quarter. Being quartered will cost you money. For this reason, you should not get into a raising war on the river in a multi-way pot with low only as one of the other players may also have the low. Example: There are three players in the hand. You start raising and you end up putting in and additional $20 in the pot as do the other two players. There is $60 in the pot from the three of you. One player turns over high and collects half the pot of $30. The other player turns over a low hand that ties you. You get $15 apiece even though you have contributed an additional $20 to the pot. You lost money by raising.
If you have an Ace and a deuce in you hand and there is an Ace or deuce on the board, you hand is counterfeited if there are not four low cards. Since you must use two cards from your hand you will need to have three different low cards on the board or your hand will not count as low.
Your ultimate goal in Hi-Lo is to scoop the pot. Since you have four cards in your hand, you can use any combination of two for the high hand and low hand. You may use two cards for high and two different cards for low. The ideal situation in Omaha is to have a hand that will win both the high hand and the low hand. The other way to win the whole pot is to have the highest hand and have no low hand possible.
that you are not breaking any local laws. It's up to you to know the legality of your actions when you gamble.