I like the curve of the back and thighs you've depicted. As for where to improve, I suggest making sure your proportions are accurate. The upper half of the body is too small compared to the lower half, and the head is even smaller in relation to the upper body. Try working on the proportions before you start focusing on anything else-- it is hard to make a pose look good if the proportions are not correct no matter how much you work on the piece.
Best of luck!