I don't care whether they're men or women, that's bullshit. A good writer can get into any gender, can get into any mouth. When I write I may be a Brando creep, or a girl laying on the floor, or a Japanese tourist, or a slob like Richard Speck. You have to be a chameleon when you're writing.
I have found that the characters in my novels stay with me after a book has ended. I know them in some sense. I never map anything out. I just think until I am secure in the voice of one of them, and then let the character unfold.