Love the way you did that messy, sweaty hair. I would watch your value changes going from dark to light, especially on the upper lip and the darkest shadows in the ear. Also, the edge of the profile from the top of the forehead down to the neck has the same value and shade all the way down. It almost looks like an outline. that's a big no no with portraits. You might want to vary that some. Overall though, it is beautiful.