I did this a month ago or so and i still need to no if it needs any improvements!
so pls dont hesitate to make suggestions pls!
:P

The stock is unclear, and definitely needs to be cleaned up. If you don't know where, just look at her fingers on the left side, and the crazy color gradiations on her leg. Definitely needs to be cleaned up. The moon in the background looks kinda wierd, see if you can't replace that with anything else...or just try blending it into the background more. The only texture you have on the wall is the glow thing around her, and a couple cloud things...try expanding that in the background and maybe less of it around her.

Not too bad of a start :o (remember it always helps if you link/show what you created this from :p)

for the extraction, one might complain that it wasnt the cleanest job~ ill use the hair as the main example. notice how the border thickness varies? what i believe should be more of a 3 curve where her hair parts you have as a flat ) curve... did you also paint over some of the lines in the hair? xD while i find the fadeout effect at the tips of the hairspike nifty, the flat white is rather dull =/

you may want to brighten the character a little to bring out the engravings on the sword more

the last main thing for me to pick at is the blue waves :p i reckon you should add some depth to them with some shading, the flat blue color and especially that one sharp rectangle edge towards the middle/lower left seem very... newbish ^^;; shading ftw!

keep it up \o/