The circular technique applies mostly to figure drawing, but can be used otherwise- too- The method is to outline with circles and ovals each little plane and form and then shade and accent.
First Step sketch in lightly the big forms and planes.
Second Step into the large ovals work in the small planes.
Third step shade and accent forms.
A 17th Century Italian Drawing which uses the technique.
A Michelangelo drawing that uses the technique, Last Judgment. Studies for an angel and for the damned, detail (1534-5) Black chalk. British Museum, London.