The typical blonde bomb shell agent has been done many a time, and I feel this is just one of those pieces I'd see in a collage of them. I feel the anatomy could use work which is why I'm glad you've called this practice.
You called this 'realistic practice,' but I feel it's a call for anatomy work. For one if that much of her breast is exposed, her nipples would definitely be visible. Secondly, as much as I am a huge fan of ladies with large hips, her legs would definitely snap with these proportions. And the hands could also use some work. Look at pictures of women with proportions close to the ones you want to draw, and your work could look SO much better. I see potential.
Also as for references go, get some good pose references as well; looking at a model picture isn't cheating! xD By doing so, it adds so much to the art. My rating is only so low because as I said room to improve, but you have good ideas; I have to give you that much.