One of the key areas that weak players make mistakes in when playing Omaha is how and when they bet the river. The river is one of the most crucial times in any pot limit game, as it is usually where the very big bets (which tend to decide who is a winner or loser at the end of a session) go in, and thinking carefully about what you should be doing on the river is crucial to long term success.
The river is one of the most critical parts of Omaha. The nut hand has been established, the pot is usually pretty large, and players hand ranges are pretty well established.
One of the best examples of this is river beet sizing. Weak Omaha players tend to just constantly fire out pot bets, yet frequently on the river this is a mistake. By reducing your bet sizes on the river down to between half and three quarters of the pot, you make your opponents life much tougher.
This is simply because you can extract much more value when you have hands by giving your opponent a better price, and also means you can throw in enough river bluffs to keep them on guard and calling too often. Losing pot size river bets to miss timed bluffs can prove very expensive, and reducing your river bet sizes both saves you money when bluffing, as well as making you more money when you have hands, through your opponent calling more often.
Another very useful tactic to use is river check raising. It is very tough working out what to do against players capable of river check raising without the stone cold nuts, as it becomes much harder for you to make thin value bets and bluffs. People will often throw out bets at you in Omaha if checked to with pretty marginal hands, reasoning that if you had anything strong you probably would have led out. This creates the ideal situation to make river check raises. These bets also have the advantage of usually pricing your opponent into calling in the end (due to the pot being so large and most of each player's stack being in), which can force them to invest far more money in the hand than they would have if you had just led out.
The river is one of the most critical parts of Omaha. The nut hand has been established, the pot is usually pretty large, and players hand ranges are pretty well established. Forcing mistakes in these conditions if what really separates good and bad Omaha players, and thinking carefully about when and how to bet the river is one of the most important aspects of Omaha.