They should be spread in two separate groups, with a "hole" (for landing) in the middle. You want the hole to be right where your shooting zone will be, with the other decoys off to the side. About duck placement, you don't want them touching. Group drakes and hens, but again, not touching.

You can mix the teal with the mallards but keep the wood ducks seperate. I wouldn't completely mix the teal and mallards though...you can put them next to each other but somewhat keep the teal together and the mallards together.

If your huntin small water like a sluogh or pond you will only need about a dozen decoys take about half dozen mallards and 4 woodducks and 2 teal most of the teal allready headed south in my part of the country. Hope this helps and good luck.