I've been reading Giovanni Civardi's excellent book Drawing: A Complete Guide and I really like how he does his portraits with a style that is at the same time exact, but loose and relaxed. The cross hatching is methodical and beautiful, but fast and expressive. A bit like in my other favourite book, John Raynes' Drawing and Painting People. I thought I would give this a go. I used my Derwent Onyx pencil (medium), and it did take quite some effort to get the darker shades, which on thin paper can buckle the paper a bit. I'd still like to order a the dark version of this pencil and try that out.
It has also made me think about how to sketch someone smirking - what is the crucial thing to include in the sketch that differs from a closed smile? It depends on the lighting, of course, but I think a smirk involves the lips being pursed and pushed out, and the chin jutting forward slightly. Plus the usual things that accompany a smile, such as raised cheeks, dimples, wider mouth and slightly closed eyes.
Pursed lips are shown by the shadow above the mouth stopping before the lips, so that there is a line of blank paper above the top lip, and slightly deeper shading under the top lip. This is due to light catching the lips more because the lips are pushed out, smirking. Usually in a sketch, the edge of the mouth's lower lips are not drawn, but are implied by the shadow on the chin under the curve of the lower lip. But in a smirk, there might not be as much shading on the chin (in this case, almost none) under the lower lip, because in a smirking smile the chin is being jutted forward so much.