First of all, you do know how to use colors well. They don't look out of place, and are pretty soft and subtle.
The anatomy of the face is a tad out smushed of the left temple. Makes the eye look like it's being cut off. May sound a little weird but this is what I normally do;during the stage of when your blocking the head imagine a tight rope it around it. This rope creates pressure squishing the cheek more outwards, rather then inwards.
As for the shading I have some suggestions for that too. Think about where the light is coming from when shading. This way the shading isn't all over the place. Another thing is about the colors you use for shading. From my experience, and from others that I've heard of, it's better that you don't just use plain black for the shading. It might reduce the zest and life out of a drawing. I would normally take the main color that you want, and then change the hue of that color, and darken a little instead.
Sincerely, and hopefully serving a pinch of salt,