Drawing an object in direct light: learning highlight, halftone, core shadow, reflected light, and cast shadow.
Inktense watercolour pencils on a Strathmore, grey-paper sketchbook. For tips on how to use watercolour pencils see: http://lynnechapman.blogspot.co.uk/2012/10/how-to-draw-with-watercolour-pencils-10.html
THE SKETCHBOOKS OF AUSTIN BRIGGS. Holy crap this is some mad pencil skillz right here.