Hi! First of all, I think you have a cool painting going on. There's a few small things that I can thing of that you could do to maybe improve it. I did this quick paintover to show you.
The first major thing I'd do is extend you canvas at the bottom so that it doesn't feel like you character doesn't seem to be standing directly on the edge. Next I feel like the whole thing is a bit static for such an epic shot. So maybe changing the pose a bit (leg position or having the wings wrapping a bit) could add a bit more dynamism. I'm not sure if the change I did are actually better, but maybe it'll give you an idea. Oh and I believe that her feet are a bit too small too.
Next, I feel like the character doesn't quite blend well with the scene. In a scene like that, where the environment is mainly one color, that color should affect the object in the scene, especially in the shadows. So having your shadows going more towards those blue-green color would help with that. Same with the light. You have a very strong lightsource with this lightining bolt, so it should also affect the colors of the areas it lights up. For example, the lighter parts of her hair would probably look duller than what you have.
Lastly you can probably add daker clouds to the foreground to add more depth. Speaking of clouds, I didn't do it on my paintover, but you could maybe also play with their shapes to add more interest and dynamism to the image. Like have them swirling around or just varying the sizes. Maybe looking at references of thunderclouds could be helpful.
That's pretty much all I can see right now, so I hope this helps a bit. I look forward to see where you take it 
