Maintaining a bookshelf
Dust off the bookshelf, this is just a once a week thing, dust the sides and the top of the shelf to make sure there is no build up. Also remember to use a microcloth so there is no scratches on the shelf. Also remember to give the books a small wipe, this can prevent any extra dust build up that is hidden behind the books. Also remember to look around the shelf and put away anything that doesn't belong on the shelf so that there is no build up clutter.
Sometimes you need to do a deep clean
Remove everything that you may have on the shelf, this is whether you use it for book or for photos and ornaments, push the shelf off the wall slightly then give it a full clean by dusting all the way around the shelf and the floor behind the shelf, even if you need, use a vaccum cleaner for a thorough clean. Now its time to give the books a proper wipe down, each book individually give a wipe all around and then place back, even photos must be wiped down properly. Your next choice is how you set up your books, by author or size that is up to you. For your photos, this is purely about using the space and aesthetic, this is all up to you.