I grew to hate three images Em had for the cover of The Ghost of the Moor (thanks, Laura, for the correction!), so I just said, “Sod it. Let’s experiment!”
These two are rough sketches of a woman. Note: I didn’t have a sketch pad in my bag when I was in the waiting room at doctor’s, so I used a pad of Post-It notes that I had in my bag.
So here goes (seeing how cartoon-like those women look, my drawing skills really are crappy. I’m sorry):

I thought she looked a bit evil, which might be off-putting.
(I’m not sure why it came up green-ish. It was supposed to be grey and pale yellow. Am too lazy to correct the gamma.)
So I created another, but it wasn’t any better:

That was when my mind simply fell apart and so, I scanned those sketches in and abused Photoshop to see what it’d come up with. Here’s the result:
Yeah, I know. (head desk)
I’d better crawl to bed and pretend I didn’t create that. Maybe some time during the night I’d have a better idea. Probably not, but I’m hopeful. Well, I have to be because I have only three weeks left. Where did time go, damn it?

Could you use the outline of one of those faces and superimpose it on the photo of the moor so that it looks like a ghostly woman on the moor?
Maybe not such a good idea?
Nah, it wouldn’t work. Thanks for the suggestion. I recently decided not to be so lazy and just do it, such as a proper drawing or a watercolour. I’m waiting to hear from Em about the exact period setting of the story. When I’m done with it I’ll upload it for you to point-and-laugh (or despair).