You've got to feel sorry for the undead. It must be terribly difficult to cope with rotting flesh and bones jutting out everywhere. Fortunately for them, though, Faine on the EU forums has stepped up to help her fellow undead with an excellent array of beauty tips. (It's worth reading throughout the thread to catch questions asked and Faine's excellent replies.) However, even though I'm sure you're going to click the link and read it yourself, I can't help highlighting this excellent post by Faine herself.
There's no shame in asking how we get that beautiful crimson tint to our lips. The answer is quite simple, really; I always carry a handkerchief and a little mirror with me.
That, and I don't actually wear lipstick.
You see, after I've eaten one of those delicious nightelven corpses, my face is usually entirely covered in blood. That's why I simply use my hand-mirror and my handkerchief to wipe away all the blood that isn't on my lips, returning that pretty crimson color.
Of course, blood does get old, at which time it grows a flaky brown. The only solution I've found sofar is to eat alliance people on a regular basis so that I can give my lips that fresh coat of blood that I need to look my prettiest.
Does that answer your question?
So, as you can see, if you have any pressing questions about undeath, Faine is the one to ask.
Update: Sorry, folks, but this post is on the EU forums which means only EU players can add to the comments! Still plenty of entertainment to be had in reading it, however.