All effective descriptive writing is fueled by character and is in the essence a form of interiorization. What is seen and described is purportedly not seen and described by the author, but rather through the eyes of the point-of-view character; thus everything that character sees must mirror what he or she is feeling. If you character is angry or upset, what he sees of, say, a room will be different than what he sees when feeling calm. In the first instance he might well notice bits of lint lying about and and annoying glare on a polished floor; however, if he is calm he might notice of the same room its relatively well-kept appearance and the pleasing abundance of sunlight.