You're water hunting it sounds like, check out this link:

http://www.dccl.org/information/ducks/decoys.htm

These are the basics (mostly applies to field hunting, but also can be applied to water - I quit hunting water a few years ago because I found the field to be more predictable than transition sloughs, withthe exception being shooting birds off the roost, which is a sin in my opinion).
1) Birds will want to land INTO the wind (wind in their face allows them to slow down and drop easier)
2) Create a landing zone (this would be the opening of the "U" we're referring to) the opening of the U should point WITH the wind so when birds come to land they will come into the opening of the U with the wind facing them. Likewise, if the wind is low that is why an "X" configuration works nicely because you aren't really sure which way they're going to land and you now have 4 openings instead of 1.
3)You can either sit on the sides or the back of the U. I prefer the back since we usually have 5 hunters in coffin blinds and we don't want to be shooting at each other, but the sides work as well - although you're concealment is then more important as the birds can see you easier. If you're set up in an "X", we put the hunters in the center.
4) Put your best decoys on the outside (the tips of the "x" or the tips of the "U") - that's what the birds will see first as they're approaching. For example, we have Big Foot Full Bodies, GHG Full-Bodies, and Carry-Lite shells. We'll put the GHG's on the tips of the U, the Bigfoots make up the sides of the U with a few near the back, and then the Carry-Lites are all around us at the back of the U. We then place a few small families outside the U to make it look realistic and use GHGs for those as well (don't want it to be a perfectly symmetrical U - imagine how fake that looks from the sky). Also, if you're just starting out - don't think you need to go out and spend your whole paycheck on Big Foots and Hard Core fullbodies - yes they're nice, but you can still get geese with Northwinds and Carry-Lites. It took us a while of saving to pay for the spread we have now (but we still got geese during school when we couldn't afford the latest and greatest).
5) Use FLAGS - they're cheap and work great, especially if you're not a great caller. Quit flagging when the geese get close.
6) When you're scouting, take a close look at the birds through your glass - are they grouped in family groups (probably this time of year with 3-6 per group). Notice the separation and how far the birds in each group are from each other, and how far each family is from one another.
7) Make sure you're in the right spot! Just being in the right field isn't always good enough - make sure you're on the right hill, revene, etc... Get a cheap spotlight and when you go to setup shine it down and find the goose droppings from the previous day to make sure you get on the X. Geese are smart, especially the resident locals that are being hunted this early. Many have been feeding in the same field for days or even weeks. They've moved around in that field to find the most thrown over grain or feed and are in a given spot for a reason - get on the X.
8) Don't be afraid to adjust the spread during the hunt. If the birds are coming in from a different direction and landing on the outside of the spread - maybe your opening isn't wide enough. If they're landing out in front of the U, maybe you're U is too deep. But, if they're coming in nice and then turning (flaring) at the edge of the decoys - they're seeing you or something fishy about the decoys.

Good luck!