Neat idea there Boni.

Have you tried tracing paper on a photo yet and scanning the traced image?

Enlarge a colour photo on a b/w photocopier. Turn the copy upside down (that way  your brain see's shapes and doesn't say thats a nose)  trace that using a light pencil. Now ink the trace Keep the inner lines nice and thin using a biro, and make the outer lines fat using a marker pen.

Put a a couple of sheets of white paper behind the trace and scan it. (otherwise the scanner lid will show through). Take the scanned image and flip/mirror it so it's the right way around. Next tidy up up any gaps in the lines and marks from the scanner.  

Now repeat for the background but don't ink the images, just a meduim pencil work. In your art software use lighter shades with no lines and theres a  

Now flood fill or use textures as fills. Instant Mucha [http://en.wikipedia.org/wiki/Alfons_Mucha].

Or if you want  that line drawn style like on dance music albums and ashtrays.  Pose a figure in poser print it to A4 size against a white background then trace and scan the body. Trace/Scan the real head from your photo and composite to size.

Pinky - you left the lens cap of your mind on again.