Mythtaken and his training collage

[Sublimus]

That last one is a good start! If you're feeling stuck, I think it might be because you have not clearly defined a lightsource. It kinda-sorta looks like there is one coming from the top right, because of the light on his forehead.
So just choose that as your lightsource, and have everything on the top right be in light, and everything on the bottom left be in shadow. Thing of the head has a sphere with one light on it. And then cast some shadows from the nose, and the head onto the neck area.

I did a quick little paintover to show you basically what I mean.



Hope that helps!