The baroque anatomy on display here is a pretty clear sign of having traced from other work.
The particular pose in use suggests tracing, be it directly or indirectly, from a couple of different sources. The particular way the torso is posed puts me in mind of some of the promo renders of Kasumi from Dead or Alive 2, when she was posed in a bikini. However the rest of the body is obviously from somewhere else, and I can't put my finger on exactly where.
Anyway, my point stands. If this hadn't been traced or if you hadn't tried to mash a few different sources together, she would not have a ridiculously thick neck, gravity-defying boobs and either a somewhat twisted spine or the posing ability of a contortionist. It would do you well to take some time studying the anatomy of the human body and what it is and isn't capable of.
Out of the many sexy pony pics seen here on DA, can't begin to describe how awesome this is just seeing a stunning pin-up piece with a bikini, this one definitely going into the fav collection, lol.
Besides that though damn at what your artwork here gunslingerpen, something of a talented artist you are to be able to handle the full body of a women and even more add a touch of Twilight to really drop your jaw, bless you.
The whole image really shows some great detail when it comes to your anatomy, from the hands on thew right hand in front of her to the way the hips and legs manage to stick out, its hard as hell to take your eyes off her.
Also like the way you drew out your image with no black outlines. Still can't get out of that but amazed always to see how much softer and even smoother the way coloring and details can look, especially yours here. o0o
For what you call practice though can spot alot of work done to detail Twilight up with the same streaks of color in her hair, the enchanting and beautiful look of the purple glow from her eyes, just remarkable.
Find it especially pleasing the skin and your focus to the sense of light and how well it manages to perfectly wow up that busty body even more. Plus catching the areas like the stomach and places where the shadowing stands out more the lacking of light, just incredible gunslingerpen, keep up the epic artwork.