A savvy Designer can instantly create a color palate that suits the mood of the space. From there you'll want to think about function. How is the layout of the room archictecturally? How can you take advantage of the space? What are the challenges? What kind of lighting are you looking for? What is the room ideally meant for?

After that you can get to the fun part that comes naturally to a professional designer. Repetition, balance, symmetry, shape, color, and textures.