I like that you've asked the question "How do I improve it?" rather than "Do you like this?" I too believe that compliments are nice, but constructive critiques and suggestions help you grow. Keep in mind that this is what I would do ... others will always have different opinion.
My 2˘ --
I like the overall lighting, but would agree with the previous comments that it could use a little more "kick." If you added some kick with your light, the whites of her eyes wouldn't stand out as looking too Photoshoped - either than or tone down the eye whitening a bit.. Also, I like that you tried to capture the feel of the dress in her makeup, but in my opinion, you were too timid. Bold stripes on her face (matching the dress) might have really made an interesting statement. Finally, I might crop in a little tighter.
Hope you don't mind, but I took 10 minutes and played around with your image to see what I could do. Here what I did -- crop the image tighter, boost the contrast to pump up the colors, then copy a small piece of her dress and expanded it to make the background more interesting. I finished the image by putting a small drop shadow to add some realizm be\tween her and the background.. I don't know if you think this improves your image, but it's what I would do with 10 minutes of Photoshop time.
