Be careful “sorting” photographs that a deceased relative already had in separate envelopes or boxes. It can be tempting to organize them when you are beginning to identify them, but remember that re-sorting them may cause you to lose forever clues that were contained in that original sorting.
If the original envelopes and boxes are not preservable, store them in the same way you found them.
This old mailing envelope contained a whole cache of photos that were only partially identified. Fortunately most of them are individuals that I know. The envelope was one of several in my parents’ things. Every photo in the envelope was a relative of my paternal grandfather.