As funny and tongue-in-cheek (pun intended) as Hazelnut's node is, I've actually published erotic novellas under five pseudonyms. I'll compare my results to the five step program.

Step One: Give yourself a classy-sounding female pseudonym.

Most folks do this, and all five of my pseudonyms are either generic (initials and a last name) or full female-sounding names. Two have Facebook accounts and all have their own websites. One uses a picture of my wife while the rest use original paintings for the images of the author. Since I've been using them a while, I did make a mistake by making full-on personas for the pseudonyms. Should one of them suddenly become the next Nora Roberts or Erica Jong, or should one of the novellas accidentally win a Rita Award from the Romance Writers of America, it will cause some blowback because readers will be irked that their favorite mommy porn was written by a graybeard named Rancid_Pickle.

Step Two: The Protagonist.

Mostly right, as far as how I write. All my protagonists are women, all of them have flaws that make them relatable to the reader, and all of them are active in what they want. A protagonist who is basically a Real Doll who is used, abused, then dumped (at least "on camera") is a weak character. She may have had that happen in the past, but this story will be about a change to her life. She learns, she discovers what she wants sexually, then she geoes out and gets what she desires.

Step Three: The Male Lead.

There are plenty of sub-genres in the erotica field, and one of the most popular happens to be about billionaires who encounter a working girl (either variety) who catches their eye. This is the basic "Person of power notices person with no power and they learn from the encounter", and hopefully vice versa. There are many, many, many series that use this one premise over and over. I was thinking that folks would get bored, but apparently not. They should be hunky and have some flaws, some of them concerning, but they will learn to treat others better by the end of the novella...if only for a little while.

Step Four: The Sex.

You'd be surprised how true Hazelnut's statement about ripping off other folk's sexual encounters is. Sex is sex, and many authors just look at someone else's stuff on Amazon Kindle Universe and copy it to get rich.

Wrong.

The sex has to have some kind of connection between the characters beyond bumping uglies. It is a stylized and idealized event for the most part, but having something like a wet spot and who gets to sleep on it can be used as a source of levity, which can break the tension as a half-step to the next scene. It also works towards building the bond between the characters.

The toughest part is to avoid purple prose and to come up with different words for the human bits. Many times one doesn't have to directly name the part getting stuffed inside the other part because we know what they are. 

Jack crammed his enormous twelve-inch manhood into Jaqueline's miniscule quim.
 or
Jaqueline felt Jack enter, the pressure building up until suddenly he was fully inside her, the sensation of stretching almost too much to bear.

One is a boring "part A is placed in part B", the other is more involved and includes sensory details. Yes, it is enjoyably cringe-worthy on purpose.

Step Five: The Plot

Yes, you need a plot. Erotica is more than just "get to the fucking parts" unless you're in a hurry and need a quick masturbation sidequest. Erotica should be erotic, and that means bringing in the emotions and needs of the characters. The difference between a person who writes erotic-ish step-by-step fanfiction and a working erotica author who earns a living from writing is the plot and erotic situations. People will return to a story about how a MILF librarian found herself involved with the college quarterback, a situation that turned into ongoing sexual encounters as compared to Jane who has a delivery guy show up at her front door with a sausage pizza when she's horny. The first plot generates fans, while the second scenario generates snores.

Step Six: ???

Get your work edited, then proofread. Get a good cover that does not get your work tossed into the Amazon sex dungeon. Naked tits and ass? Dungeon. There are a lot of things that can cause Amazon to hide your book, so consider "going wide" and publishing in several ebook outlets like Smashwords or one of the websites dedicated to erotica romance.

Step Seven: Profit!

You would be surprised how much you can make writing erotica. Focus on writing novellas that have a complete story arc because you can write three of them for every one full novel. Explore a series, like a nymphomaniac construction traffic flagger who enjoys having trucker sex on a lonely Wyoming two-lane blacktop paving job. My wife and I used to come up with erotica plots whenever we were driving to sci-fi conventions and comic cons. We have spiral-bound notebooks filled with plots. You can write three or four erotica novellas in one NaNoWriMo. Once people find out they like your work they will go through your back catalog. If you have twenty novellas or more you will have plenty of sales assuming you can write a decent story.