You really need to work on the shading, specially on the hair and that's pretty much it tho.
The hairstyle you designed are based on some anime character, eh? Looks quiet familiar but it's well designed.
You just need to work on the hair details, like those extrahair on the back-side and the sides with black lines on it it's kind of too stood out without any color shades imo.
Goodluck with your more heads tho, kinda looking forward to see them in the future.
Also, your art motivated me to draw in 1024x512 next time, somehow.