Royal Road marketing/promoting requires more work than writing your stories. You need to get access to the biggest authors and then convince them to give you a shoutout. Yes, there are invite-only Discords which usually only invite people who already made it and have a decent audience to contribute to the others. If you don't have that DM like crazy on RR and those less desirable Public Discords. You need 30 chapters (10 instant release and then 20 chapters in the next 20 days). After that, be prepared to release at least 4 to 5 chapters per week.
In addition to that, you need even more chapters to make your Patreon viable, so I'd say at least another 20.
So if you are gunning for a great start, prepare 50 Early chapters, line up 50 shoutouts (Not from people with less than 300 followers or so, you need BIG stories).
If you want to spend money, buy some ads. Also, you need to choose an awesome cover and need to have a great shoutout/blurb that people who read those 50 stories that shout you out will feel drawn to.
Usually, it takes many months to prepare a good launch. You need a ton of chapters, you need 50 shoutouts lined up and confirmed, and then you just have to follow through.
The goal is that you manage to get on the "RISING STAR" list, which is their trending list. Usually, your story will remain there for a few weeks, and that allows you to rapidly expand your audience. 500-1000+ Followers for the first month is quite realistic.
From there on it's to slowly but surely build upon your success and expand your audience and hopefully run a successful Patreon.
Overall, your story does not even matter that much. It needs to be interesting and have a certain standard, but being successful on RR doesn't mean you have a great story to offer. It means putting in the work.
I spent a long time learning these things. If you want to know more, feel free to DM me or talk to me on Discord. I always love complaining.
