Okay… third attempt to post… (lost two other detailed critiques due to timeout)…
You seem to have a good sense of aesthetics. You know what you want in your drawing and it comes through. You’ve got a good eye for working with digital coloring. Also, kudos for posting your work here… the quality of work on these forums can be very inspirational, but also very daunting.
That said, there are a myriad of issues relating to anatomy, perspective and proportion in this drawing. Here are some notable items:
- The character’s right arm is too short.
- The character’s right shoulder is abnormally stretched/extended.
- The character’s head and neck are off-center to her left on her shoulders.
- The character’s right breast is placed too far to her right, and not positioned accurately.
- The character’s left leg seems to be twisted abnormally.
- The character’s feet are nebulous, and it looks as though she is standing on tiptoe.
In general, there is a battle going on between a front and a three-quarters view of this character. For example, the character’s abdomen is facing off to her left, but the navel and lines look to be facing front.
When rotating a character in space, all forms have to rotate as well. The left arm, in addition to being too short, should be overlapping the body. The left breast, which would be in the way of the arm, should be out of the way, slightly overlapping the left breast. This is due to the various forms of the body working in perspective.
Looking at your pencil drawing, I’m not sure how you structure your drawings, but starting out with an action line and placing the basic forms, then adding in the details is a good way to work. Also, try to picture the forms before you set pencil to paper, then draw them as you see them in your mind. Remember that the human body is a collection of solid, three-dimensional shapes, and that the rules of form, weight and perspective apply to them all.
To build up your reference for drawing the human figure, a good life drawing or anatomy course is a good idea, or at least a solid book on figure drawing or anatomy. Once you begin to understand how the human body works, your drawings will progress at an amazing rate. Once you know the basics, applying those basics in your own style will produce the result you’re aiming for.
Quick reference for the arm: stand and let one of your arms fall to your side. The elbow should be roughly on a horizontal line with your abdomen, and your wrist should be about mid-calf on your leg.
Hope this helps. Best of luck! 
P.S. - A suggestion… work on the character first, then worry about the background. And, if possible, practice drawing your own backgrounds, rather than photoshopping an existing image. It will help you learn to place your character(s) in space.