Best method / material for signing matted and unmatted photographs?

I am pretty sure it is up to you. Personally, I like signing (my initials) on the photograph itself. To me, it is like a painting that way, with the initials and year hidden on the bottom left or right. Maybe take a trip to an art museum so you can see what others have done. But I think it is entirely up to you.

There’s no defined way to do it. I know some people who insist on signing and numbering the print/photo/whatever and not the matte because they want it to remain on the piece (though I think some of these people have delusions but I digress). Aesthetically, the coolest look I’ve seen is a flat black matte with a thin silver paint pen for the signature.

back of the print and on the undermatte. Never on the overmatte because it can be removed and tossed easily.

Thank you all!