Once you find the perfect spot you need to figure out how you want to pattern your duck decoys to best get the ducks to pile into your decoys. I have found the "J" pattern to be especially effective on diving ducks, and to a lesser degree on puddle ducks.
The basic premise is that you set the majority of your decoys in near your duck blind at the bottom of the J. Once you have set those up I usually just pick one side and let the wind blow the boat downwind and decoys one at a time to make the straight line of the J. In this setup it can be beneficial to have the long string of decoys extend far outside of shotgun range as the idea is to get the ducks to cruise down the line and land next to the large group next to your blind. Some people gang rig about a dozen decoys to make the line, although I don't as I think it is more trouble than it is worth.
Again, I have seen this setup work exceptionally well for divers. They will follow that line right up to your spread. Puddle ducks, especially mallards seem to want to land outside the farthest decoys not allowing a shot. Give the pattern a try the next time you are out on a diver hunt, you will find it helps to bring them up close and personal!