go shooting first. try out some trap and some skeet with the shotgun, as is. go with someone who knows shotguns.
i personally find i'm best with just a bead sight ro no sights at all, as long as the gun fits me ok. years of trap and sporting clays, and i just mount the gun to my shoulder properly, focus on the barrel for just a quick moment, and then i can point shoot better than most people with sights.
this works for me because i'm a much more natural point shooter, with both eyes wide open, than a target shooter. for the life of me i can't get my handgun groups down to inches cause i keep blasting away at center of mass, and never look at my sights.
in paintball, i find i shoot better from the hip than from the shoulder. the hopper disturbs my sight path, so i get the whole gun out of my face.
in other words, get to know yourself first, before forcing yourself down a particular path.