The white reflections on her mask look too blurry/smudgy, so I recommend making it sharper. Also you should remove the reflection placed between the eyes, the focus of the drawing is the girl, not the white blur. Try toning down the white, because black and white are contrasting colors, making the white pop out.
If you really want to practice drawing, I'd recommend using a program on the computer, because layering is important in drawing.
I think you did pretty good for using your phone though. Sorry if this didnt help lol