In hold’em, a player can use one, two or none of his hole cards to create his final hand – if there’s a royal flush on the board, every single player in the pot at the end will receive an equal share of the pot.

But in Omaha you must use two – and only two – of your four hole cards in forming your final five-card poker hand. This rule leads to all kinds of curious situations. In hold’em, you would love to look at your two hole cards and see two Aces. In Omaha, if your four hole cards are the four Aces (or any four of a kind), you essentially have a ‘must fold’ hand (unless, perhaps, you are playing heads-up), because you have a pair of Aces and no way whatsoever to improve them. You can’t make a flush or a straight – you must use two of those Aces – and clearly another Ace can’t hit the board.

Indeed, most hands that contain just three of a kind are completely unplayable, although in a high-only game you might consider trying A♠-A♥-A♦ (a pair of aces and one nut flush draw) from the small blind in a multi-way limp pot, and in high-low you could also play A♠-A♥-A♦ because you would almost certainly hold the only A-2 (you’d also have one nut flush draw, and while your pair of Aces doesn’t add much to your equity, you would be the only player who could hold a pair of Aces).

I vividly remember the first time I played Omaha, in a private game about 25 years ago. The final board showed K♥-Q♣-K♠-Q♥. I had an A-J in my hand, so I had a straight, and I called at the showdown. My opponent, a friend in a friendly game (even though the stakes were £10-£20), held up a lone card, a King, and I tossed my hand towards the muck.

‘What’s your other card, Eddie?’ asked a more experienced player who knew full well it was my first time out. Eddie showed an Ace, meaning he had three Kings with an Ace kicker, and not the full house I was accustomed to that King meaning in hold’em. I protested that I’d held a straight, and because this was a friendly game, Eddie actually gave me half the pot. I’d been ‘entitled’ to all of it, of course, but if you muck your hand in any kind of serious game, what you’re entitled to doesn’t matter.

This is why it’s vitally important to ‘table’ your hand (place all four cards face up on the table, without mucking them) in any situation where you’re not completely sure what you hold. Once you table your hand, other players and the dealer are entitled to help you read it. This assistance often pays dividends, and there’s nothing to be ashamed of. I have seen players at the final table of a World Series of Poker event staring at the same Omaha hand, all trying to figure out what the hand’s owner has!

The 'must two' rule means:

• You cannot ‘play the board.’ You can only play three-fifths of it
• You cannot play a single card from your hand (the ‘Eddie rule,’ as I have come to call it)
• You cannot play three or four cards from your hand
• Just because there are four suited cards on board and multiple players in the hand, it isn’t a ‘lock’ that someone has a flush, because ‘someone’ will have to hold two cards in suit, not just one.

You must get accustomed to thinking of your Omaha hole cards not as individual cards, but as groups of two. With four cards in your hand, you hold six possible two-card combinations. A strong Omaha hand gets equity or value from as many of these six combinations as possible – ideally, significant value from all six.

Good hold’em players know that position – playing on or as near to the button as possible – is vital.

So much so that many hands worth a raise in late position are not even worth a call in early position. In Omaha, position isn’t irrelevant, but it pales in comparison to hand values. It would be fair to say that hold’em is a game of position, while Omaha is a game of card combinations. Why is this so? It’s because…

You should make sure all your hole cards work together. Although not a great hand, the A♦ is supported by a 6♦ and 5♦, which could be used to make the nut flush.

Even though every once in a while the ‘must two’ rule will devalue a hand, as in the ‘Eddie’ situation, where his solitary King didn’t give him the full house it would have in hold’em, over the long haul, the typical winning hand is much stronger in Omaha than it is in hold’em.

The reason is obvious: instead of only one two-card combination that can be used together with the board, the player has six such combinations possible from his four cards. Someone playing A♥-K♥-J♦-9♠ and staring at a flop of Q♥-8♥-2♠ may be focused almost entirely on his nut heart flush draw, but if a 10 hits the board, the player has made a straight with his J-9 combination.

Good Omaha players don’t focus entirely on one part of their hand. They examine all the little bits and pieces of equity that each of the combinations represent. This is one of the reasons why you may have heard the expression ‘Don’t play Omaha hands containing a dangler.’ A dangler is one card that doesn’t work together well with the other three cards in your hand.

For example, if you hold K-Q-J-10, your cards all work together well. The six combinations will give you a straight with almost any combination of high cards on the board. If instead you held K-Q-J-2, the deuce is a dangler. While it could help (if, say, the flop comes 2-2-4, which is still a pretty vulnerable hand), it's far less valuable than a card that adds to the straight possibilities, because Omaha tends to be a game of straights, fl ushes, and full houses – at least at low stakes, where many players stay in, or in PLO, if the pot is going to grow very large.

Hold’em players are accustomed to hands like top pair, top kicker being strong (for example, holding A-Q and getting a flop of Q, 5, 4). In Omaha, top pair, top kicker is practically useless, unless you're only sat down with one, two or – at a push – three other players. Even then, you shouldn’t be raising or even calling big bets with it. Indeed, in games where many people see the flop, a good rule of thumb is to assume that if a hand is possible, someone either has it or is drawing to it. When only two or three players see the flop this isn't true, but with six people in, players are trying to match 24 cards up with the flop (36 two-card combinations). Good Omaha players, in multi-way pots, play hands that are either the nuts or a draw to the nuts.