One way of organising them - online or off - is to scan them save them all in one place. Then go through them all, tagging them with as many keywords as you can think of. E. G. The year, the names and surnames of everybody in them, where they were taken. Holiday snaps, wedding, christening, school photos, portraits, uniform, animals, other objects (the grandfather clock, the penny farthing, the piano, the old jalopy)
That way they organise themselves - you put in a key word and up come all the pictures which you have tagged. You can then see e. g. a series of photos of Susie growing up. Or all the pictures taken in 1934. Or all the pictures of horses, or mucking about on boats.
Good luck with it!