Francis D.K. Ching is an incredible artist and author of the best architectural drawing drawing books. He also has a wonderful blog called: Seeing. Thinking. Drawing, drawing thoughts and observations. He is posting his drawings from his recent travels from around the world.
Also on the blog, he has notes and explanations of how he uses the principle of design. Here is a quote explaining about his use of contrast in this drawing. This from his September 21, 2012 post “An important principle that can be applied to any drawing, regardless of the style or technique one employs in its execution, is the principle of contrast. Without contrast, we see none of the differences that contribute to identity and meaning—distinctions in line weight, tonal values, textures, details, and the use of white space.”
One of my all time favorite book is his Design Drawing with Steven P. Juroszek. I am fascinated with techniques for communicating visually. This book does an outstanding job with this topic showing examples. The chapters include “Drawing from Observation, Drawing Systems and Drawing from the Imagination” You will discover amazing illustrations explaining techniques of designing with drawing and if you are like me, inspired to practice and learn. Check it out!