This just reminded me that I was going to draw something for Halloween too, eventually. I was planning on drawing Saeko from the anime High School of the Dead.
So now the picture; the only thing that bothered me here is her waist. Maybe it's because her arms are covering most of it, but it seems too skinny to me. Other than that, it's still a very fine drawing. I'm jealous of how good you are at colored pencils. >_>