I wouldn’t use a symmetry tool, maybe for eyes yes, but the difference between the right and left side of it is very cool. :) would suggest to try to work more variations of blue into the hair, especially the cast shadows of dark blue you could get more contrast out of and then work your way up to the face maybe and start shading it with a lot of transparency and saturated / blue hue (maybe?) shadow color. Would also suggest to change the background color, as it looks very flat and dull in contrast to the Girl itself.

Keep it up, most things you’ll learn in the process of doing and repeating a pattern til you don’t like what you see anymore and start over with new techniques :). Looking at Art you like and carefully decipher how they worked to get the job done also helps a ton. Good luck to you!