First, you have to understand what Omaha is. It's about redraws, redraws and more redraws. Having the best hand preflop means almost nothing and having the best made hand on the flop means just about nothing as well unless the board is of a very rare and non-drawy texture. The best hand on the flop is often the biggest draw. Why? It's simple, you've seen 7 cards, so there are 45 unseen cards. If you have 15 outs, you're 33% to hit on each street. That means you've just become a favorite to win the hand with two cards to come. Of course, it's not that simple. Often, you'll be sharing outs to a split pot or, even worse, your outs are dead to a better draw, such as a higher flush draw. The key is picking spots where you have outs to the pure nuts and letting go of hands where you appear to flop huge, but your hand is actually a big dog. An example might be where you flop the nut straight without a redraw and there is heavy action on a flush draw board between two players in front of you. Regardless of having the nuts, your hand is a dog. While I don't have time to go into all the rules of profitable Omaha, I'm going to explain how to understand the keys to picking up a big draw.
The ideal flop in Omaha is probably top set and nut flush draw. The reason I say probably is that it's a relatively hard flop to get paid off on unless someone flops something like middle set with a flush draw. Needless to say, it doesn't happen often. The good part is, you basically can't lose unless someone hits a straight not of your suit or you get one-outed by an underset. Against a flopped or turned straight, you have an enormous re-draw to a flush, full house or quads. It's not hard to see when you've flopped top set nut flush draw, so I'll move on.
Here's where things get a bit more complicated. Straight draws. Unlike flush draws or sets, straight draws can present themselves in a number of different ways in Omaha. There are five different straight draws that you can flop with 8 outs, 9 outs, 13 outs, 16/17 outs and the big daddy full wrap for 20 outs. Of course, if you put a lot of money in on any of these flops, you can be assured that you're either splitting some outs with someone or someone has another big hand of some kind. Nonetheless, we'll take a look at how each one can present itself.
1. There's the typical hold em “up and down” straight draw for 8 outs.
For example: AA78 on a A56 flop.
In this situation, you have top set with an 8 outer draw to the pure nuts assuming no flush draw. This is a great hand, but if you have A268 on a A79 flop, then you should be very cautious as your draw is very weak.
2. There are situations where you can have three cards to hit for a straight.
For example: KQJx on a ATx flop. You can hit a K (three left), Q (three left) or a J (three left), for a total of 9 outs to a nut straight.
This is a fairly powerful draw when combined with a flush draw. If you have KsQcJsXx on a AsTsXx flop, then you've flopped huge. Even if you have the K high flush draw, I'd recommend putting a lot of chips in. While you can certainly see additional cards without a flush draw, you should be cautious if a flush gets there or the board pairs. Ideally, there won't be two to a suit on the board when you flop this hand without a flush draw.
3. You can have four cards to hit for a straight. I call this a quarter-full wrap, although I don't know if that is a technical term.
For example: 2458 on a A36 flop. You can hit a 2 (three left), 4 (three left), 5 (three left) or a 7 (four left) for a total of 13 outs.
This is getting to the point where it's a huge draw, although you should be careful on a flop like this as not all of your outs are to the nut straight. This is a VERY powerful draw if you flip the cards to the top of the spectrum to something like KJT7 on a AQ9 flop. If you notice, you still have 13 outs, but all four cards will give you the nuts as a K, J or T will give you the A high straight and an 8 will give you QJT98 with your hole cards in play in bold. Combined with a flush draw, you can't flop many bigger nut draws than this.
4. You can have five cards to hit for a straight. I think this is known as a semi-full wrap, but the terminology isn't really important.
For example 79TJ on a Q86 flop. You can hit a 5 (four left), 7 (three left), 9 (three left), T (three left) or a J (three left) for a total of 16 outs to a straight. This can also present itself as a 17 outer on a hand like QJ8x with a flop like T9x. In this case, you can hit a K (four left), Q (three left), J (three left), 8 (three left) or 7 (four left).
If you notice, the way to hit a flop like this is to hit exactly in between and around your cards, like so: 6789TJQ – hole cards in bold. The key to this not being the biggest straight draw possible is that your hole cards aren't perfectly split apart due to the 9TJ being in sequence. One thing you might notice about a draw like this is that you start to get into trouble with endpoints, which reduces your ability to have nut draws. For instance, with the quarter-full wrap, you can have almost every out be to the nuts as I demonstrated in the analysis. With this flop, you simply can't flop as many nut draws. More specifically, it's harder to flop a lock nut flush draw because you can't be holding an A (also known as an endpoint in the ranking system) and flop this type of straight draw. You could take my example and move every card up one rank to achieve a nut flush draw when you have the K of a suit and the A of that suit flops, but that's the only way to flop a nut flush draw.
5. You can have six cards for a straight. This is the ultimate 4-card Omaha straight draw and it's known as a full wrap.
For example: 79JQ on a 8TK flop. You can hit a 6 (four left), 7 (three left), 9 (three left), J (three left), Q (three left) or a A (four left) for a total of 20 outs to a straight.
Just to have another look, this is what this draw looks like when lined up in sequence: 789TJQK. Note that this time, you've flopped a hand where the flop fits into your hand and around your hand perfectly. In a similar fashion to the semi-full wrap, it's impossible to flop a nut flush draw with a full wrap, although you can make a nut flush with the K and A of your suit on board. However, it's pretty hard to get paid off on a flush board with the A and K out there and you're holding the Q and possibly the J. Even donkeys won't pay off huge with a T high flush.
To wrap this up, understanding your draws is very important in Omaha. It's also important to study what types of hands have the capability to flop certain types of draws. You might notice that once you reach the quarter-full wrap, there are only a fairly small number of hands that are even capable of flopping that type of draw. They become even rarer when you get up to the full-wrap draw. I'm confident that any thinking player who learns to fully grasp draws in Omaha will soon become a profitable pot limit Omaha player at even the highest limits.