This is one GREAT drawing tip that I always tend to use.
To shade:- To make it look like the person has contour, you can shade it with the pencil, then, smudge the place shaded with your finger...(rub on it). We do this so that it could look like a shaded area, it will make it look fabulous!
Try to make it look different:- Don't copy anything anyone makes, try to make it unique by adding shades, cold and warm.
Freehand "Drawings" are used to supplement an oral description may be rough and incomplete.