Hey Dasha! I love this portrait! I just corrected a few areas that I felt looked a little odd, like the eye, or simply tried to emphasize the volume a bit more using only lines. Areas such as the upper lip should be shaded, since it's not exposed to the light in the same way as the lower lip. I think a cast shadow underneath the nose, as well as around the eye area, would work well. :) You can also emphasize the AO areas, such as between the jawline and the ear (although I think I may have emphasized it a bit too much). And in general, use thicker lines in areas of shadow and AO. Hope this helps!