Hey Chaos, very nice start

I wouldn't feel bad about starting just with grayscale, IMO this is a fine way to separate the challenge of value and color, and most serious painters do a charcoal value study before they start slopping paint around anyways. That said, your values are pretty good here but I feel are too close to the photo to be engaging or as helpful as possible. Now that you've recreated lighting similar to the photo, think about how you can tweak it to give the image more depth, and communicate the basic forms you are rendering more clearly. E.g. currently the nose, jaw, and neck all appear to be on basically the same plane; how can you use the basic grayscale values to help distinguish these forms?
I think the image could also benefit from cleaning up some of the noise, and working with larger areas of value.
great start!