Why shoot a vertical head in a horizontal format, remember this is for a modeling site, so the more model seen the better.
With short hair, better to show only one ear, shirt on models right a bit bunched up. Think dynamic, both head and body are square to camera.
A rim light on models left side would punch this photo up a bit.

I wish you well

I think key light should have been the other way, on the model's left.

You could put a rim light on him, or you could flop the main light, I'm not sure if those moves would help or not. You could increase the exposure level, but Edward Weston would argue that what you have is perfect, so there are two schools of thought on that one. Imagine however that you're Irving Penn, and you flag off the background on the highlight side of the face so the background goes to black. Then you place a soft light on the background of the shadow side of his face. Now you have highlight against shadow, and shadow against white, that way you add incredible depth and contrast to an already nice image. I think your image would be awesome done in the Penn style.

I personally shoot everything to a cinema proportion, so I like the horizontal composition.

The composition is good. If you can,  during a shoot,  smooth out the ridges on a shirt on camera left, it would creating another leading line to the summit of his powerful face. That aside, it has the imprint of an interesting and potentially powerful style.

You seem to like darkness more than I do.  But if it sells, fine.  Is it an image the model picked for himself?

The illuminated ear is too prominent,  I would suggest building a small scrim to cut the light hitting the ear.

Speaking monochrome - This is dull. You want to bring out the tones, make this dramatic as I can tell you want a fierce look with the eyes.

Read this: http://www.techradar.com/how-to/photogr … ng-1320967