When you’re all set up and ready to use the blinds, you want to travel to the tent, and wait for a few seconds if you don’t see any ducks, but chances are the game has spawned in a full group of duck on the location and not the small groups you get when calling for them. And you should ONLY use birdshot, since birdshot is so dang cheap this method is extremely cost efficient. You should also bring the duck caller in case when you travel to the tent there are more duck flying overhead.
For the loadout you don’t need much at all, you get three free shotguns when you buy the Duck and Cover DLC so you should purchase them all and equip them, this way you don’t have to reload after just 3 shots.