It might not look it, but I actually spent a few hours on this tonight.
I was trying out a new program called ArtRage 2.0. Bascially it's a paint/pencil/whatever simulator. It simulates canvas grain, paint blobs, mixing, smearing, etc. You can see a little of the texture it created in the shoulder and legs.
Unfortunately I was using a demo version, which meant that several key features I need (such as instantly 'drying' paint or layers) were not available. Luckily the full version is incredibly dirt cheap. I'll be trying it out again later.
So I loaded it into Photoshop so I could overlay the sketch and do a little precision spot shadows.
Nowhere near a finished piece... but interesting.