This is list of what you need for reloading no matter what press!
Reloading Manuals of the real kind not the freebee ones! Get those for cross reference material!
Press - Single Stage to me is the best way to learn before advancing to any kind of progressive, Turret or Progressive
Shell holders (if the die set doesn't have them) Or the appropriate caliber conversion for the Dillon
Tumbler along with media and polish of choice I like IOSSO
MTM makes great loading block tray that handles most cartrideges
Case Lube (you won't need if using carbide dies but you will if they are rifle carbide dies my choice for rifle is Imperial Die Wax, but Dillon spray lube works too)
Case Neck Brush
Case Trimmer (Lee works, but Possum Hollow is better, Wilson makes the best hand powered Lathe trimmer, and Giruad is the best powered Trimmer)
Primer Pocket Cleaner
Priming Tool (I like the RCBS, but Sinclair makes the best)
Powder Funnel kit with drop tubes!
Powder Measure (nice for faster powder charges)
Hammer Type Bullet Puller
Ammo boxes and labels
A notebook for recording your results
Reloading rifle rounds on the 550 or 650 is not as straight forward as it might seem!
Rifle brass tends to lengthen when shot. Case length in excess of max can cause a spike in pressure. So, the best way to load say 223 is pre process your brass. That means that you size your brass, trim the brass, then chamfer/debur the brass, and then deal with any primer pocket crimp, and clean up the primer pocket. I have not cleaned up the primer pocket of pistol ammo, but I do with rifle ammo, this avoids a high primer and possible out of battery ignition of loaded round. Then I tuble the cases clean. Then in the first station in lieu of sizing die, I have universal decapper. This cleaning out any errant tumbling media. Then you drop your powder charge, seat your bullet. and crimp at a seperate station. Crimping and seating are two different operations. For a uniform crimp a person needs to have their brass at a uniform length.
One thing to remember is that the Dillon powder measure does not like stick powders, and might want to hand weigh precision rifle ammo rounds!
Just go into the Gunstop, and John will get you set up with the right stuff!