Draw what you actually see and not what you persume! Observation is one of the powerful tools for sketching. I began to see the world with an eye of a designer while i started sketching in my routine life. Never ever before I thought of the manufacturing processes or mechanisms of the things around me. Sketching from Orthogonal views and Perspective views to the final product realization sketches made me realize the fact the art is the best form to pitch your ideas and in fact the best marketing tool. Learning the art of sketching was a great learning Gaussian curve at Duke.