Hey rick,
nice work on it so far!
in case you're down for some critique
(I know it's only half done but it looks like it only needs refining)
First I'd suggest some darker shades (some reddish hue) in general when toning his skin color.
Also, his 5'o clock shadow is pretty noticeable and interesting similar shades with his top buzz (which is pretty black) and
it sort of rides up all the way to his sideburns.
His iris seems to be a little bigger and blacker too, I sort of sculpted the eyes so that it would be covering some part of his iris (
https://www.imdb.com/media/rm3871509504/nm0000243)
here's a collage reference I used when sculpting to show what I'm talking about in terms of color.
https://img80.imageshack.us/img80/1972/collage6w.jpg
hope this helps
looking forward to some paint ups of this dude