One tip maybe is bigger eyes. When I first saw it, i thought the eyes looked a bit small underneath the hair. Other than that, nice job!

- Try new things like shading or different lineart.
- Try to imitate other artstyles you like.
It sounds strange, but it's really
helpful to find your own artstyle.
- Study things like anatomy or colors.
It's easier to draw something
if you know how it works and looks.
- Try to draw other things you never/rarely draw.
Example: If you draw mainly humans,
you should draw some animals or
other creatures like dragons etc.
You could start to draw them in a cartoon-way
and then in a more realistic-way.

Well, I hope this helps?
You could also watch some
playbacks of other Colors-artists ^^