Check out J Thorn's advice on writing dark horror and post apocalyptic fiction, and while you're at it, go get his guide to post-apoc and his new book "American Demon Hunters."
The Post Apocalyptic Readers Guide
American Demon Hunters
BIO:
Thorn earned a B.A. in American History from the University of Pittsburgh and a M.A. from Duquesne University. He has spent the last twenty years researching mysticism and the occult in colonial American history.
http://jthorn.net/about-me/