If you're playing Omaha Hi Lo then one phenomenon you're going to come across before too long is that of a player getting "quartered". At some time or other it's probably going to happen to you as well.
When you get quartered it means that you only win a quarter of the pot, instead of the half you were expecting. Most commonly, this occurs when two players turn over the same low hand. The best hand wins the high half of the pot, while the two hands which tied for the low portion get only half of that each - a quarter of the total pot.
This is clearly a bad thing to happen because if there were three players in the pot then you will typically have contributed a third (33%) of the pot, but will then receive only a quarter (25%) back - which adds up to a losing situation in a hand where you turned over a winning set of cards!
An even worse scenario is that you were heads up against a player who actually won the pot for the best hand and then split the low hand pot with you. In this case you would have contributed roughly half (50%) of the pot, but received only a quarter (25%) back.
Players get quartered more in the low hands because the hand ranking system is so much simpler and because most players will always get involved in the action if they have A-2 in their starting hole cards. Whenever these starting hands run into each other and there is a qualifying low hand then somebody is going to get quartered.
The only real way to minimise the danger of being badly quartered is to not let the betting get out of hand if you suspect that any of your opponents are betting into the same low hand as you. That doesn't mean that you should never raise when you've got a low hand, only that you be wary of the effects of being quartered if you feel that your opponents are showing signs of having the same low hand as you.
Of course, if you're also confident of winning the high hand then raise away to your heart's content, because even if you split the low hand you're still going to end up with 75% of the total pot, which is a great result for any hand of Omaha Hi Lo!