There's not much to it. Just make sure you're using steel shot that fits your gun. Every body has their own personal preference as to the brand of ammo. about the only rule of thumb is to use #4 shot for your smaller birds (teal, wood duck) #2 for regular duck ( Mallard, Gadwall, widgeon) and BB,BBB is mostly for goose but I have known a few ppl to use BB on duck. It's all personal preference. I know guys who buy 10gage shotguns and use #2 magnum loads for duck and I know guys who will shoot 20gage #2 shot. Me, i'm right in the middle.
By the way, you sure you want to be a duck hunter? It is 1000 times more addicting than crack cocaine laced with meth and heroin. ~