One of the first things you do when determining what paint color you're going to use is to decide what features of the room are permanent, for example, cabinets, tile or a brick fireplace. Emphasize the room's architecture such as crown molding or arched window treatments with lighter or darker paint. You can also make one wall an accent wall by painting it a different color. When painting several rooms, you can unify or create separate spaces by using a common color, using different shades of the same color or choosing a different complementary color. You can also use paint color to make a room look wider, a ceiling appear higher, a small room feel larger or a large room feel more intimate. You also need to remember that depending on the time of day and the natural light coming in or the type of lighting you bring in such as lamps and candles will change the shade of the paint color you have chosen, giving you an active choice in creating the mood you want for your room.  

Blog inspired by article featured on Realtor.com and can be seen here: http://www.realtor.com/home-garden/painting/painting-wallcover-ideas/choosing-colors.aspx