I'm going to leave proportional/anatomy issues alone cause I'm sure others will want to beat it in to you on there own. So stepping away from that line, I'll start a new line on perspective and composition... and maybe a little color thrown in to spice up my gumbo.
So far you have tossed in a couple different perspectives with out thinking of how you are going to place your character in to them. Focusing on the one that actually has your character, for her to stand on a slant that way she would be leaning way back, were talking to the point she should be falling down... off the roof... to what would presumably to her death...
Solving problems like this really come down to the planning stage, or its at least the easiest way to solve them. When you want to draw your character in a scene, think of the whole scene, not just the background or the character as alone entities. When working on the rough drafts, sketches and then final drafts, work them up together.
When you get to actually drawing. this will help you keep things in both the immediate background and farther out in much of the same perspective. This will help tie the scene together better and have an overall consistency.
Now you might fear that if you don't start working on the composition of the piece from the beginning, that their is no hope for it to have a future. Well, thats not entirely true. If you already have a background or character, you can add the other, but you have to follow the same angles and rules that you set up in what ever part you started with. if you don't then you end up with girls looking they're about to see what a swan dive back first feels like.
Plan ahead. it helps. you don't have to plan out every little detail for every little doodle, thank Cthulhu, but it helps if you do it for the pieces you want to organize for final pieces.
yeah to start they are a little over saturated. Especially in the background and the far background.
As things get further away from you they tend to lose their vibrancy, become more dull and less defined. Use this to your advantage to save yourself a little work on the farther backgrounds and to draw better attention to the main subject of your piece.
a couple other things. you need to work on your light sources. you have the sun behind her, she is being light from the left side.
The costume... is more fan service rather than any sort of functionality. Might want to ask yourself what kind of piece and character you are wanting to create in the future.
The background in general isn't all that great. you start to have something interesting with the buildings but then the hills just kind of ruin it. makes the landscape feel like a bunch of spheres cut in half and scattered about.
Anyway. Try and plot out your final compositions a little more and I think you'll have much better success in the future. Keep practicing and drawing, and never be afraid to ask for some pointers and help. The art forum is an awesome place to learn if f you are willing to learn and have the stomach to survive.