If you want to know how to write long published erotica romance, this sub-board is fantastic and that's why I'm here lurking. Money? As in money now? Use the
DWS Method. (Dean Wesley Smith)
Write 3k-10k shorts, charge $2.99 (Yes, people will pay $2.99 for an erotica short and you'll make $2.09 each sale) and when you have three or four in a given genre or series, put them in a bundle for $4.99-5.99. If you see something take off, write more in the series of in the same genre. You will need to learn to make your own covers from royalty free stock and write good blurbs.
You need to follow the market and not be fussy about what you write. Use a pen name, if you want to make money--this is not going to be material what you want on your resume. Right now billionaires are hot, but I think that's cresting. Gaywolves were smoking hot 6 months ago, but you can't give them away now and the whole paranormal market is saturated. Three ways and MMM always work well. Lesbian sells poorly, unless it has an out there fetish. PI (pseudo incest) is always good. Don't know about gerontophilia, but ageplay seems to sell well.
Incest and underage will not be accepted by any of the "self-publishing" (quotes as this is not the term we use for ourselves). You cannot sell these, so don't write them.
Don't do any promotion. Erotica will self-promote as you get more titles and your name appears on bought/also bought and also by this author lists. That's the real key, volume and consistently production.
Writing a constant stream of shorts and raking in the bucks sounds easy. It's not. This is a job. It requires following the market and being good at knocking out readable material at quick rate and being able to handle all the cover and formatting yourself. Also, a change in Amazon's policies could completely obliterate your ability to make money.
I know writers who make about as much off their online short fiction as they do their Etsy craft accounts: maybe $50 to $200 a month.
My partner and I have 10 stories written over the last six months. We make $150-350 a month. We would do better if they were under the same pen name, but that's life.