You can paint the walls, but it will be a bit plain, monotonous. The best option, I think, would be to pick up a beautiful wallpaper in one of the online stores. Now so many stylish wallpaper is offered and William Morris style is only one of them. However, you can and experiment, in one room to stick such wallpaper, and in the bedroom, for example, glue other drawings. The choice is now very large.