I think the best sketches utilize the art of
exaggeration,
spontaneity and
suggestion, rather than extreme detail and realism. I find a pose of the model and a certain way I draw and I use that for all my sketches, it looks especially good when designing several pieces for a collection to have all the sketches look the same.
When I sketch I try to keep the body to a minimum, I usually don't draw the head, just the chin
suggesting the head, a single line
suggesting the arms and legs, etc.
When one tries to draw the human body with it's true proportions, on paper, it ends up looking kind of stumpy and thick. So, I tend to make my models 9-11 heads tall, it ends up looking fairly natural and, surprisingly, not odd!
I also try to keep my sketches quick...it usually generates better results than if I spend a lot of time perfecting the drawing, which in turn, gives the piece an element of
spontaneity.
I also like to constantly change my style, if not a 100% change, a slight change, either in the model's pose, or even in the way it's drawn, it keeps me fresh and engaged. Often, if I stick to a certain style of sketching for too long I begin to realize the flaws in the sketch and I begin to really dislike the way it looks.
(all scanned by me)