Really most guys just want some confirmation what they are visiting is a "sex blog". So graphics don't really matter. Maybe a header with a sexy girl (depending on the Blog - is it hardcore or softcore?).
I would just search some sexy WP themes and be done with it. The graphics are not going to get you more visitors, customers or sales.
PS: The Blog I cited is very low on 'graphics' (if I remember correctly) yet it's one of the most famous ones out there. She even turned it into a book/movie.