Great use of lines, proportion and cartoon appearance. Overall it appears to be a strong sketch with good attention to detail and looks professionally done. As for something to work on, I'd suggest paying close attention to the shape of the characters hair and its layering. Although the hair design is awesome, it appears to overlap part of the face on top and appears separated from the hair on the side of the head. I don't know if this was intentional or not but correcting such could take away the translucent appearance of the hair. Overall, very good work and I look forward to seeing more of it =]