One

Function.  The first step to ensuring that a room will be effective is to decide on what your space will be used for (i.e., conversation area, dining, media room, office, etc.).  How do you want to utilize your space?

Two

Mood.  Would you like your room to be traditional, contemporary, modern, or eclectic?  Should it be warm, cool, bright or subdued?  How do you want to feel in your room?

Three

Harmony.  All of the design elements for your space should be appropriate to your lifestyle.  All furnishings, new and existing, should be in harmony to your mood and style.