Marina,
If I had a model like this for my self portraits I would do nothing else.
I think that you have a fresh and lively expression. The color scheme is wonderfully balanced and the only suggestion's are about drawing.
I have some comments, or rather insecure questionings. Is the mouth and the nose correctly drawn? I feel that the mouth is a bit wide on the right side (our right) and I also feel that the bridge of the nose, between the eyes, should be more defined, have more shadow on the right side.
I also think that the chin and neck should be separated with different values. Preferably the neck should be darker under the chin.
Just suggestions.
Allan
I