By using light curtains, allow more light to enter the living area. Instead of using heavy looking "valances" use proven and if possible semi transparent curtains that are ample to reduce glare which might be caused because of sunlight. Use brighter color schemes commonly known as "hot" color schemes. These create a very good transmission and reflection of natural as well as artificial light inside the living room. You can find one more different approach to defining the perception of the living room (or any interior space) and that's the empty volume left out after all the furniture as well as other accessories have been fitted. Because anything inside our living world is always "relative". The perceived volume is always relative to the empty volume that may be normally used for circulation. The more empty volume you get, the bigger the room will look.