One thing that I had a friend of mine do a few years back we titled "Malice in Wonderland."
She had her regular Alice Costume, but to frighten it up a bit we bought a pair of tights that had a crooked black and white checkered pattern which made your eyes go cross when you watched her walk. We also ripped the dress a bit, and added some dirt and fake blood spatters to make it look like she'd been on a rampage through the slithly toves (it's okay if you don't know what those are, only a true Alice fan would. No offense.) But for her face we did a white base make up to make her look pale, and used black make up to make her eyes appear sunken, and her cheeks contured and hollow.(Don't just use black though, a little goes a long way when you blend with the white.) A few drops of blood from the mouth and a fake knife covered in blood completed her look, though for one night out we did use fake blood to make it look as though tears of blood were trickling from her eyes.
She got the most attention of everyone at every party. Whether they wanted to go up and ask her how we did it or not, out of shear terror.
If you need any other ideas or have any questions feel free to ask me at email@example.com, as I feel that no one should go to a costumed event not feeling confident in what they're wearing. Hope I was helpful. :]
I'm a costume guru. I can't lie. You need an idea, I've probably done it.