Mine: Right
Original: Left
You were pretty good already, all you need to do is use a few layers. (The little box that you find in the lower right corner) You can add layers with the + and erase them with the -. When using layers, the one that you don't want any colour covering (Such as the lines) Go further towards the top. You can change the opacity with the little bar on the upper part of the Layers box.
You should make the hair bend like normal hair and not have as much as a triangular shape to it and more of a wavy shape. Also the bangs, if you want it to be covering the eye, you should make the bangs longer.
You need to make the face facing a general direction. The ponytail on your leads one to believe the person is facing towards the right, although the face structure leads one to believe that they are facing towards the left. The bangs also make the girl seem to be facing the right also.
When drawing the eye, nose, and mouth, be sure to pay close attention to anatomy, to make it look more realistic and clean. Keep them spaced evenly and facing the same direction.
Also, when it comes to the neck, keep it thin but not too thin. There is a small line between too thick and too thin.
And when making the face shape, give her some cheek bones! :) All girls dream of having defined cheekbones and small chins, so in art, you can make little dreams like that come true for your character.
And women don't have very broad shoulders, the pair that you put on your girl didn't make her look petite but made her a bit more 'manly'.
And again on the lines, keep them thin to make your picture seem cleaner and keep all of the skin tones you use the same, unless you are shading/highlighting.
This was just a quick sketch. This was done with a track-ball mouse. Thank you for your time!
Also! Add your siggy! Just so people cannot steal your wonderful art :3