I consider bookcase styling to be an art form. Sure, bookcases are utilitarian, a place for books (of course!) but it's also a place to show off things that you've collected, art that you love, or items that have meaning in your life.
I often revolve items on my bookcases, editing them from time to time while adding new things. It reflects a life in motion, and if the items are artfully displayed, it can bring you joy!
I have a simple (but tried and true) formula for styling bookcases that will make your shelves look fabulous:
1. Group items by color
Grouping items by color, keeps the eye from jumping from place to place and creates a more restful visual experience.
2. Layer in art
Prop art on top of books or hang it within the bookshelves -- it will look amazing!
3. Add texture
Layer in items with texture, like decorative boxes, or sculptural pieces.
I tend to put lighter feeling items towards the top of bookshelves and heavier ones on the bottom. Play with the sizing of your bookshelves by moving shelves up and down (if they can) and create asymmetrical spaces. It will look more visually interesting.
Add things that make you happy -- personal photographs, a shell from the beach, something from your childhood -- whatever it is, make sure it's joyful.