firstly, nice one papazola.
I have a tip for you, to put more energy into your head use orange tone for midtones, put a little more contrast, it is nice, and I like the shading you did, but for some reason it looks monochromatic, this wont get much of a exciting feeling.
in this one particularly you put opposite eye highlights, try it in the top of the pupil, it will look better, even thought the eyes has a depth.
I feel like you did semiprofile as intention, worked a bit like cubism for picasso.
I have a hair tip, use polar coordinates and use a dotted cross as brush, or try to make highlights in the middle of the hair, and try to avoid the place with distortion, maybe there was no option.
the black hair is mostly highlights, because the shadows wont appear and the midtones are just slight.
other hairs has different tones of colors as strands, but focus on clumps instead.
the shadows in the jaw looks so correct, nice job on that.
I still feel you did try a metal grip for hair ponytail, try highlight with white if it is the material you wish.
You are very promising, reminds me of myself when I joined gata.
keep working.