my technique would be to start with a fairly pale colour and do the red, purple, whatever shades with very thin washes ; check out the last page of my thread "rascal's random miniatures"
I have never tried it, but starting undead flesh on a black undercoat seems difficult to me.
Why would you want a black undercoat if you want a rather pale fleshtone ?
Let us see your results, ok ? I'm interested in what you'll do.
happy painting !