This is a very good first effort (much better than I could have done).
Some points to work on: The walls and floor are all the same color, making them lighter or darker depending on the light source will really help.
The demon woman needs a little more work, many of the lines on her body fade into her color. I'm linking a tutorial on how to digitally color a drawing, which may give some tips:
http://www.sailorenergy.net/HowToDra...CUColor01.html
But other than that, the final result is excellent and I look forward to whatever else you may color in the future