Hey, good one! You said that it look too cartoonist. You can easily make it better with prismacolour high quality colored pencils. Use the white and the black and you'll be able to make it really better.
The only thing I can say needs a bit of work are the eyes...they need to have a bit of more texture and a more exagerated shading/lighting...i think thatīs what makes t look a bit cartoonish...lovely work in here