I do both. I have my personal written one AND I have one on my computer also. They say TRADITIONALLY it should be written in your own hand BUT I would like to be able to pass mine down to my children and them be ABLE to read it so I type it up AND write it down. That way there is a back up. I have my families B.O.S. which of course says Grimoire on the front of it cause it has been passed down for ages however there is A LOT in it that is unreadeable due to the fact it has been passed down for SO long. I don't want that to happen to my children. And I have been going through it trying to type up a back up for it also that way what is currently legible will still be for my children and their children, etc.
It is a Book of Shadows. Which is a NEW term for it. Have you heard in ancient times of the Grimoires people had and past down through their families?? It is the same thing. It is where you keep important things.
I mostly stick to a physical BOS, though I do keep a computerized backup. You never know! As far as organization, I keep like-items together (section for rituals, spells, chants, correspondence, etc.). The three-ring binder setup works best for me, though I've seen some pretty awesome handmade books that you can undo and redo the binding if you want to move things around or add more pages.