In regards to your newest picture, spike, the style has improved.
I'd try drawing more often, because that is 100% guaranteed to improve your style. Especially if you use advertisements that feature people, it's free and very easy to frequently check your lines as you draw them.
The proportions make her look rather skinny (and in fact, rather skeletal what with what you did to her waist, and the eyes look off - try making the whites of her eyes more visible. And a big mistake people do with legs (thighs in particular) is to draw the legs' lines parallel. They curve. Look down at yourself as an example. Thighs usually go like this | / (more gently than that, though) rather than ||.
I've got to admit, I love the hair's style. Hair is so freaking hard for me to do properly.