i like the background.
i think that her waist and wrists are too small though, and that her mouth is too far over. but it all fits, so it isn't that important. it flows, adds to the style. ^^
did you make it with photoshop? they have a blur tool, one that can make it less obvious how the lines work out. i reccomend it.
nice picture. i like the eyes and the hair.

I've never thought about a cosplay pic! Great idea!!

i can't help but comment on the eyes, since you were trying out new eye styles.
seemingly this type of eye style you came up with lacks a pupil. i can't figure out your true intentions, but it does look to me that your achieving a marbled eye look. which is a great idea, they're very glossy and shining, who wouldn't like to have a marble for their eye?
but i would still highly recommend you add in a pupil, if your attempting to achieve even the slightest sense of realism. the addition of pupils will give A LOT of life to a figure.
However, if you were purposely trying to achieve that marbled eye look with your new eye style experiment, then don't take so much into account the advices i just gave you.
other than that, keep up the work and keep improving.

looks like great work
do you take critiques?
and it definately looks like you've put it in the right category.
if you take critiques i would love to tell them to you.
your definitely getting there with the eys.
keep it up
great coloring btw