Nice! I really like the overall mood of this. The first thing I noticed was that that her left arm (the one on our right) looks a bit weird. I believe it's because of the hand position. The way her arm is placed, she would be reaching to her side, but then, her palm is pointing more towards behind her. And I'm not sure if this position is possible and if it is, it's probably very uncomfortable.
I think a more natural hand position would be something like this ( sorry for the roughness of my paintover)
So with that new hand position you will have to move the dragon head so that it faces us more. Perhaps something like this ( Again, sorry for the roughness of my paintover )
I think that just this already adds a bit more interest to the composition. And then you can definitely also follow @moirae advices.
I think that this piece has a lot of potential, so I look forward to see what you do with it