Breakdown of portrait sketch

I sketched this in 10 minutes in order to demonstrate how I usually draw, for a Quora answer about common mistakes amateur artists make. I don't consider myself an expert but I realised that many people focus too much on the details. The answer is here : http://qr.ae/TUIHSS

The final sketch.

Outlined and highlighting several masses. This helps to be more mindful of how light may affect different forms.

I start with a rough, faded sketch that blocks out the shape and composition of the piece, usually with a thicker brush so that I am forced to use simpler strokes.