One of the first steps to creating good materials is to train yourself to study your surroundings. Spend some time looking around with the intent of noting exactly what you see. Look for differences in the brightness levels in different parts of a scene. Then, imagine how what you see relates to a 2D image on a computer screen or a printed sheet of paper. This is the same process you would go through to paint a scene using traditional art methods.
Realism is too full of telephone poles with sagging wires and overflowing dumpsters.
Your computer images are a form of art that should be manipulated to convey certain information to the viewer. Figure 1 shows a typical Material Editor dialog with sample materials. Maps Materials consist of attributes applied to the surface of the models that trick the viewer into thinking that an object is made of wood, cloth, steel or any other natural or manufactured material. Maps are the patterns defining various textures or color of materials such as bumpiness, opacity, glossiness or color. As a subset of materials, they don't get applied directly to faces.