What is the proper shotgun setup for hunting deer?

I have a Mossberg 500 and new to hunting deer with a shotgun (Come from MI and have always used a riffle). Most of my time with it has been pheasent hunting and I haven't shot a slug through it yet. I was wondering was configuration is best for hunting deer? I have a 28 inch barrel but also can get a riffled barrel from my bother-in law. I have 3 chokes and wasn't sure which to use? I thought I should use the full choke but also have the Modified and IMP CYL. I wasn't sure which choke to use and the setup. I'm sighting it in tomorrow. Can anyone please let me know what the best set up for this gun? I will be hunting out of a tree blind, 12 feet up, in pretty dense woods. We cut 5 shooting lanes cut but the rest is pretty dense. 50 yard shoot max. thanks!