To start, the character itself could use work. The lines are all very shaky and need to be cleaned up, the head doesn't scale correctly with the body, and the arms appear as though they have no hands or bones. You used the gradient tool far to much, giving every thing a metallic look, and there is no reason for the background to be so blurred. Lastly, the moon is very awkward looking and blurred in some parts and in others it is very sharp looking. To fix the shaky looking lines I would recommend either investing in a tablet, or drawing your pictures out on paper first then outlining them in an art program. I would also recommend looking into getting a more professional art program like paint.net, paint tool sai, or Photoshop to name a few. Because the body is all very strange looking anatomy wise, I would look into studying some on anatomy. The gradient tool and blur tools can be great for enhancing the look of a picture, but shouldn't be used as something to cover up flaws in your art. The shading is very odd because the only visible light source is the moon, but the lighting you have applied to your character is different all over the body. I'm not trying to come off as a jerk, there is just a lot of room for improvement.
Thank you for the critique, this is one of my older pieces that I posted on another account and I am currently moving everything over. I don't know what the gradiant tool is and have never used it but I agree that it does look metalic and she is lacking in figure >w< this was done on photoshop although I have improved very much since then although I am still working on uploading and it may be a little while before I can post it but it should be in the next half hour, and you can see some of my much newer art.
To tell the truth this isn't much of my favourite piece at all >w<