Practice, practice, and more practice, practice makes perfect, well near perfect. Anyways I did not do a warrior but its the same with all the others as well, at those early levels you are down to a single target until you get an ability where you can aoe aggro mobs, until then you are down to clearing 1-2 mobs any more and your dead.

If you dont have any higher toons to play you are going to be going in there and wiping alot in order to learn the instance. If you have an 80 or something run in there and get reacquainted with the instance, or run your tank solo in there if you can get a group that is.