Raises in tournaments

There are no starting hands in Omaha poker, on which you can make a raise before the flop first, because you invest in this move too much money as for a tournament. If you raise before the flop on aces, you spend very much money, and this is what you should not do before you see the flop. 

If you find yourself in a situation when someone has made a raise, and a couple of players have called, then you can re-raise, but you should not do raise first. The fact is that if before you someone has made a raise and two players have called, then re-raising on aces with connectors or suits would be reasonable, since the pot is large enough, and you can make such a re-raise, that will squeeze out someone, and will keep you with only one opponent. Then you can do raise on your aces.

In tournaments, there are always exceptions to this rule.  If you have a short stack, then you probably will raise on aces, even if you make the first move. And if you have a decent amount of chips, and your opponents are short or medium stacks, than you can put them in a spot with your aces, especially if they are short stacks. So in a tournament game, many use main exception to the rule that you should not raise with your aces in the first round of betting.