If you have too many small objects, try replacing some of them with taller items to help create a better visual triangle. You could also try clustering items together on top of a tray. Another option would be to tier them on top of a set of books to give height to some of the objects. You won't always be able to get all the small objects to look right, so you may need to assess more on whether or not those items need a place on your shelves.