How to style a bookcase.

I've been getting a few requests to share some of my tips on how to style a bookcase.

1. Lots of books in different colours and sizes.  As I'm an avid bookworm I have tons of books. I've given them a bit of order by colour coding them.
2. Mix in a few knick knacks.  Photos, ginger jars, globes, artwork, animal figures, a collection of shells, my champagne chairs and a big letter S are some of the things I've used.
3. Have a variety of heights. Place books different ways, have a mixture of high and low on each shelf.
4.Display what you love. It will make you smile each time you walk past.
5.Research. Browse Pinterest, magazines etc and be inspired by other's ideas.
6.Keep Playing. Keep playing around until it looks right. You will always change them up as you add a new book or little knick knack. They are a reflection of you and your taste. Have fun with it!

Here are some other bookcases I love :

I love the idea of wallpaper as a backing on this bookcase above. I think this works because the rest of the bookcase has a neutral/simple palette. 
What are your tips for styling a bookcase? the first 2 pics of my home are by Hannah Blackmore and the other 3 pics are from my Pinterest boards.