I love the studies mate.
Remember to flip your images horizontally (digital) or use a mirror for proportions.
I'm with you about colouring, but I've been experimenting with colour
on the side, and as long as the values are right in Photoshop, just slap on a new layer on top and set the blend mode to 'color'. Real paints though. Forget about it. I'll probably be the first to go traditional from a digital background.