I'm working on a portrait of Conan the Barbarian... the face is based on a portrait I saw from the Savage Sword of Conan
Nice...and he doesn't look a thing like Arnie...]
I would add a little 'detail', especially some fine lines/crow's feet around the eyes, maybe a little more 'pore' texture. The kind of thing that someone who spends most of everyday outdoors develops, even if they aren't that old.
good advice, but I'll probably do that with lighting... here's some brown in those to get the desired effect.
Oh, and I finally found a use for the default angry expression :)