Fame

Make other writers feel special. (cosmopolitan)

Reply to their posts, and recommend their stories at the end of your own. They will be more likely to return the favor. Piggybacking your way to the top is a completely valid strategy. Just don't be shameless about it.

That said, write a universal story. (cosmopolitan)

If you want your fan fiction to eventually reach a mass audience, it can't depend on extensive knowledge of Hogwarts. Sorry. Use things everyone can imagine and understand.

Write about celebrities, movies, or characters you love — but make sure your subject has a mass appeal. (cosmopolitan)

Anna Todd adores Tom Hanks, but a heated romance featuring him as the lead bad boy wouldn't get as many views as one starring a Harry-Styles-inspired character. Gardner thinks that Sherlock or Doctor Who fan fiction will be where we see the next major acquisition. "Those shows have a massive online following," says Gardner, "particularly in the fan fiction [world]."

Not gonna lie, I agree with the "make sure your subject has a mass appeal" part, but I understood nothing of the example, so just bear in mind to make a fanfic about hot topics that are trending and other things like describing characters by comparing them to celebrities and stuff.

Also, creating and managing a discord is a perfect way to organize your fanbase and further enhance your community as a whole.