Thanks superman, yes the shadow on his face help to the likeness a bit but I think the trick of the guy-liner removed helps more to this
Yes, I have used paint washes to change the overall skin tone at first time but then I have gone to the drybrush technique for the red areas and stubble. Finally I paint some hair on the beard and chest with a little brush, a few retouches with that.
One of the thing that help a lot with the likeness is remove the guy-liner. This is one of the more important step for the final look as Harrison Ford.
I have used a matte varnish diluted in water (MARABU AQUA MATTLACK ) with airbrush to seal all the paintjob but this make a few gloss effect, depends of the proportions varnish-water. And then, with a fine brush, I have applied the sweat effect with another gloss varnish in specific areas