That's plain? *rubs chin* Hrmmm...

Well pale as she is...there's always tattoo's on bare skin. Possibly the marks that grant her the immortal form
Come to think of it, she could probably give her self fellatio, if she was so inclined....that's just kinky

When I use Undead/Exotics, I tend to go for one particular trait that draws the eye: Glowing lines or "veins". Example, some dimly glowing blue or green lines running from beneath the collar across her shoulders, like a web or following her veins. Have some other places where it happens near the surface; wrists, etc. Places where blood flow would be easy enough to spot out.

As a Dullahan you could also go for the "Edritch Energy" sort of deal; patterns of ghostly light on bare flesh. Sort of like my "evil" South/Central American spirit:

http://www.furaffinity.net/full/14308020/

I don't know much about her.
Is she undead?
If she is, Armara necromancy can help reattaching her head permanently xD
She makes me feel uneasy with her detached :s