in my case i digitally paint. (occasionally i scan a colored pencil drawing and go over it with a digital brush). this means my own brush and pencil strokes create the image one the screen as if i was doing it on paper or canvas. i literally draw on a touch screen. (think windows old paint program, except a slicker adult version). my computers screen doubles as my sketchpad.
the process for this self portrait is one i use in most my work, whether digital or not: i begin with a pencil drawing, add basic blocks of color, add shading, dark and mid tones, then add light tones and miscellaneous details.
thats a bit of a look into my workflow. :)