A) Birds will be where they want to be. I cant tell you how many times despite my decoys and calling the birds landed right over there, for what seems like no reason at all. That being said, If you are in "the spot" the birds will land there with just a couple of decoys and minimal calling.
B) Call to wing tips and tails. NEVER CALL TO BIRDS COMING TO YOU. They will spot you and they will flare.
C) A duck would never win a duck calling contest in Stuttgart. No stupid hail calls and no "feeding calls". Get a simple double reed and learn to do a simple quack and to do a 3-4 cadence quack.
D) Use a IC or mod choke. 2, 3, or 4s steelshot.
E) If there are no ducks around, take a leak, pour up a cup aof coffee, of adjust the dekes, those actions will bring in a suicide mallard from 3 counties over.
P.S. Before you shoot a duck, think about how youre going to retrieve the duck... (water depth) and if the "dead duck" starts swimming away, aim for the head.