Nice work at first. 
If I can have some advice, try to search pose references from the internet. You have not got a solid knowledge of anatomy yet, and in these characters it is the most important thing. It is not a problem, don`t worry, it is all about practising, but until that when you learn the basics of the anatomy it will be better for you if you see a lot of human poses maybe in Pinterest or somewhere else. I can recommend you this guy who make a lot of tutorials about drawing human body.
The proportions the base colours and the idea is good (I do not understand exactly the floating skin, but it is cool, and surprisingly odd 
). The layout about your concept sheet should be more organized maybe it would be better if you would organize the three side of you character next to each other, but you can figure out an individual layout too, but it should have some sense.
About your character: try to imagine a background story for her. Who she is, what is her name, why she have a floating skin, what does she do, she is in the dark or the light side (maybe the dark, but in this stage it can be both of them) and so on. It is make you more easier to identify yourself with her and do better work. And do a plenty of skecthes! About her, about her clothes, and weapons. It will be cool, keep cool, straight to the bright future! 
