Here's my caricature version of Harry Mulisch (Dutch writer)
The first sketch is done with 2B pencil on paper. Then scanned and made an overlay layer in Photoshop. The yellow ochre was my key color. From there I build it up in one layer with (hopefully) harmonious colors. I don't work with many layers in Photoshop like some other artist do but I try to treat it like a real canvas. Working from thin (transparant) to thick (opaque).