What other colours and patterns are in the room?
What is the surface you are decorating? Is the wall you are papering old and bumpy? It may need re-plastering or covering with lining paper. Or are you painting wood? Do you need a primer? If you already have a decorator in mind, we recommend seeking their advice as well before making any final decisions.
Do you want the wallpaper/paint to be the main feature or do you want it to blend subtly with your scheme?
Think about the size of the room and ceilings, as well as if the room is north or south facing as this all can have an impact on which colours and patterns will work best.