I have gone about this one thus:
1. I sketch the face and vital features withe a brown Tom Bow dual brush marker.
2. I then use soft pastel by Winsor and Newton to bring out some basic tones and colour.
3. When there's enough pastel all over the piece, I retain the main drawing marks with the oil base pencil.
4. While using this black oil base pencil I try my best to give the piece some vibrancy and sensitive strokes- things I really like in lines.
5. I then introduce some more detail with my graphite H pencil, it is hard and can produce etch like lines to bring out forms without obliterating the pastel below.
6. I then introduce sanguine oil base pencil to liven up the black dull lines
7. Finally I add some highlights with soft pastel again and call it quits before further destruction
8. This whole piece is done in high tempo with a lot of whacking and hitting to produce a spark of life, something I strive to achieve when transforming these sketches so they won't become static transformations but still retain some of the vibrancy of a sketch!