Decluttering or tidying away

I am trying to 'clear the space' for my business. This is a challenge as my 'office' room is barely 6'x8' and I have most of my book collection in here. The book overflow is in the front bedroom (that's just my books. Paul's books are downstairs in two tall bookcases.

I threw away a wheelie-bin full of paper last year, before I moved, and got rid of some books then too, so what I'm doing now is more of a tidy-up. So, I'm trying to declutter, but there is little I want to throw out at the moment, so it's more of a tidy up and trying to find spaces to put things. The problem is that there aren't any spaces that are not already filled with stuff.