I completed this portrait of a little bit.
Sometimes when I paint something, I see that something is wrong but I can not understand the problem, and no matter what I was doing the wrong thing does not change for the better. The same happened with this painting.
But now I know, I just sometimes lose control of the tone and the only way to see the mistakes is to convert the image to grayscale, or put on the top layer of a white/black fill and set the blending mode to "color". The strange thing I knew about this simple method, but never used .. argh. Now I've learned and added a layer with a white fill in each new work.
I promised to upload a video process, but I do not like it anymore. I will record something more simple and better next time.