first off i say that you're off to a good start. you've got a good eye for detail and style. i think the biggest thing that bugs me is the stance is kinda stiff and awkward. i don't think very many people would like to pose like that naturally, especially if the main focus is the style/attitude that you're trying to give off. probably what would fix it up the most would be to have a line of action or having a sense in where the weight is being distributed.
i did a crappy drawover/sketch to kinda show what i'm getting at.

one thing i picked up in drawing gestures is that the weight is almost always distributed to one side more than the other. it's a lot more uncomfortable to stand at attention than it is to stand at ease. a line of action can help when you start drawing your figures. it's a simple line that'll go from the top of the head to the bottom of the feet. a nice curved line to help plan out how the body will sit. my first sketch shows that. it doesn't have to be anything fancy, the important thing being that you use it as placement for where the weight will go. i opted for her right side (our left) because in your sketch that's where her hips seemed to jut out more.
once that's established the next thing would be to plan out the angles for the hips, shoulders, and head. a lot of times i'll counterbalance the hips with the shoulders, which gives a natural pose. so if the right hip is the highest point, i'll make the left shoulder the highest point. it keeps it from looking unbalanced and/or the feeling that the character is falling in addition to having the figure look less stiff. if you want to go into more detail you can also angle the shoulders and hips into the 3/4 view to create a sense of depth since your sketch everything is pretty much straight forward, which also gives it a feeling of awkwardness and stiffness. in this case i also decided to have the head tilt the opposite from the shoulders to give her more of an attitude. smaller lines of actions can help with the appendages like arms and legs.
the next thing (which is also the fun part for me) is planning out the outfit. personally i kinda like that outfit...something i'd probably wear if i could, ehhhe. i think what'll really make this stand out is how you overlap and the folds on the cloth. what i tend to do is break them down into simpler shapes...cylinder cone-ish shape for the skirt, maybe a 'c' shape for the open shirt to give it that form...basically thinking in cylinders in how objects will wrap around the body. with clothes like these though it's a bit easier since they're not very drapery. things like stockings and anything form fitting i like to see a break in the line. like for the fishnets in the second sketch i did i made sure that you can see some of the overlap happening, and paying attention to how gravity works with it. from personal experience thigh highs that are held by garters will have gravity affecting it (in addition to you moving around) so they tend to slip...hence the reason for garters. so the highest point would be where the clips hold up the fabric.
i like the play between loose and tight with the outfit you made, and it'd be nice to see that exaggerated. like with the baggy stuff made really baggy to contrast with the tight fishnet, like seeing the skin kinda bulge out from underneath. if you also look up reference for fishnets you can really create a sense of form and shape by how you draw those lines. i tried to recreate that before, and it's a lot of fun and creates that edge of sexiness if you can do it right (i'm still trying to figure it out):
i think it's a pretty good sketch, the shape of her isn't stick-like, which i think adds a lot to it. i think that you can do a lot with the hair, especially if you want to put it over her eyes. you can break up the shape of it more and then have wisps of hair flying around, or maybe even caught between her lips (since hair that long has a tendency to do that). i'd love to see her not cropped off at the bottom to see the rest of her outfit.