Interesting, but visually confusing - I mean that the choice of sepia with a grayed "ghost" doesn't "feel" ghostly somehow. And as nearly as I can envision it, neither would the reverse of this. I also find the irregular sepia splotches on the "ghost" distracting, particularly the one over her eye. The styling is excellent, though. [Headstones are a bit modern and clean for her dress, I think.]
Not sure what to suggest constructively. I think taking the picture in the shade, with a light background, makes it a bit difficult to effectively lighten the "ghost" relative to the background. But I've never done anything like this, so what do I know?
Keep trying. Anybody who gets vampires as nicely as you can surely get ghosts as well.