It's likely to be a work in process forever, but I've tried an assortment of things and am currently moving toward standardizing on 16 x 20 inch metal frames of very modest cross-section (in matte black). I use two 4-ply mats, with the opening in the outer mat about an 1/8 inch larger at the bottom to allow a signature (modest and in pencil) on the reveal of the inner mat. (I also sign the back of the print with the date in case anyone cares years hence.) Again, lately, I hinge mount the print behind the window, and hinge the mat to another piece of mat board and or heavier backing board to make a sandwich to slide into the frame. My "plan" is to reuse the metal frames and store the matted prints in clear bags. At my current low level of productivity, that should suffice for a while.
At home, many of my prints are hanging in a hallway that provides a textbook example of what not to do for exhibition, so we'll ignore that!