Do or don't? Rainbow books
Type 'rainbow bookshelves' into google and do an image search. Do you like what you see? I do, but I realise it's not for everyone. In fact rainbow bookshelves tend to divide opinion within the interiors world, with some people thinking they are great, and others calling the whole thing a trite trend.
I personally think sorting your books into a spectrum is an easy, therapeutic job that you can do in less than an hour, and which will have a positive impact on your home. An alternative would be to colour block your books, having green on one shelf, yellow on another, as seen here.
If you feel it looks a bit primary school, then why not have a go in a child's bedroom, or playroom? Remember, if you don't like the result you can always reverse it with no harm done. Plus you could kill two birds with one stone by filling a carrier bag with books you no longer love as you go along.