If you are placing room furnishings then you must take care of light as dark cabinets will disappear in dimly light alcove. Similarly bright pieces will garnish under picture windows. If you are furnishing your room then you must have a clear idea about its use as if you typically eat or drink there then is there enough places to put plates and cups downs.
Is there any place for keeping books and CDs? You can mix hard and soft surfaces with rugs and table covered with fabrics. Then next step is selection of color scheme. If you have decided about the color used in the room then you should bring samples at home and look at them in day light and at night, in both natural and incandescent light and while selecting any color scheme, you must keep in mind that dark colors will fade over time more than light colors.