If you have a lot of books you will have worked out a way of storing them in your bookshelves over the years. You probably never have thought about the best order. A very common mistake is to sort the books by size so that they look nice and clean. The disadvantage is that in terms of author and contents they will be completely mixed up.
The best way to store your books is as libraries or book stores do. They group them by author or by theme so that you know where to search for a book reducing the time to identify it. You might even create a catalogue or inventory of your books.