How to decorate a teenage girls room?

Hello!!My daughter wants to decorate her room but it is a very awkward shaped room.Well,it is a small square shaped.On the back wall there is a slanted roof.On the left wall is the en-suite.On the right wall is a window.She also has a queen sized bed,a wardrobe,a desk,a chaise,a, dresser and a few cuboards in her room.Please give me a few ideas on how to decorate her room.Thanks so much!!