Tone document and rough sketch
I fill a document with a mid-tone grey, which enables me to judge my values (light and dark) more accurately. I create a new layer above the grey background and label it Rough Drawing. At this stage I draw loosely. Keeping it rough speeds things up and means I can try out new ideas without any restrictions. I explore proportions and spacing of features.
Refine the sketch
I reduce the Opacity of the rough to about 30 per cent and create a new layer labelled Refined Drawing. Now I find the details of the design – wrinkles or nose details, for example – that need defining. This stage is key, because the drawing will serve as the blueprint for the rest of the rendering process. Good draftsmanship is the first step to great paintings!