Most Helpful Guy
You're an awesome artist. Good job!1
Most Helpful Girl
Not bad, but there's still tons of room for improvement. I'm currently a student who does manga art (small commissions and such) as a side job.
Anatomy and coloring are both issues I can see here. Even when stylized, human anatomy and proportions must show through to create artwork that is pleasing to the eye. To help elaborate on the points I will make here, I redrew the piece (though, it follows a style more similar to my own. It's purpose is to show my points in use.) and also drew over your piece to point out errors. (Paste the link and remove the parenthesis)
Redraw: (https://prntscr). com/awv81h (Quick sketch. Time - 15 minutes)
Overlay: (https://prntscr). com/awv01h
The first thing I noticed was how large the hair appeared. Hair doesn't fall that far around the head normally, unless it's styled into an updo. Considering the way it was drawn (longer down the sides), I'd assume that this isn't the case. In my overlay, I drew where the top on the head should be and how far above the head the hair should fall from. Also, the eyes don't line up with the rest of the face. All facial features should be mostly parallel. I drew in lines to show where the features should be touching, however, one eye is especially crooked regarding these lines. They are essential for facial balance. Lastly, the face shape seemed warped. The cheekbones were not a mirror image of each other (on our right side, the bone seems to be up by the eye, but on our left, the cheek falls near the side of the mouth).
Color errors fall in shading and color balance. At first, I though the frame around her head was hair. This is because the colors are very similar, and used near each other. Hair isn't so solid. With more flow-y shading, the hair would appear much less like the frame. The drawing is also pretty flat. Even "cell-shading" (which refers to very harsh shading in which little blending is used) can improve appearance dramatically.
Keep working on it! With a few more years of practice, I can see you mastering these concepts. If you need any extra help, feel free to leave a message ^-^