Before you read this blog post, let out all of your childish laughter when you hear the word sex. Now, proceed to read:
When I write I love to add an element of psychosexual horror. Why? Besides the fact that I love sex, I often feel like nothing drives a monster more than depraved psychosis infused with sexuality. Take for example, Jeffrey Dahmer and Ted Bundy, these two men were driven by bizarre mental illness and lustful fantasies.
But with all this said, there is line between writing a great horror story with sexuality and flat-out cheesy, nasty erotica (clears throat* Fifty Shades of Unexperienced Fan Girl.) Here is the way I see it: If your story has to rely strictly on depraved sex and killing off characters to keep the plot going, then you're doing something wrong. Also, when it comes to writing about sex, one has to be careful that it doesn't take away from the story.
Sex is what you make it, whether it be passionate and love, scary and disturbing, or even both. The goal is to not make it cheap. Another thing to remember is to make the sexual writing sound realistic. For example, if one writes about a prostitute, the liberated business woman of pleasure would not refer to a penis as a "thingy" or a "ding-dong." This goes for a sexually active man. Would a man-whore call a woman's vagina a "wussy" or "woo-hoo?"
Make sure your NSFW writing doesn't fall flat with over-used sexual slurs. Make sure to describe sexuality as something sensual, not a "pink power unit" or a "big angry dick." Avoid making it comical, unless that's what you're going for in a genre. Even still, the point is for the reader to take you serious and understand that you are writing for the sake of art, not the script of some sleazy porno.
Always remember, if you're going to write about a mature subject matter, then you have to be mature about it.
PS, Fifty Shades of Grey is a great example of how to write a bad erotica. I seriously recommend that all sexual writers read the book to get an understanding of what not to do.