Let sensei do the talkin.

→ Covers do count. 'Don't judge a book by it's cover', it's just that matter of sparking interest and being drawn in. Covers do that. Covers are the things that visually capture your attention and make you look at the plot and everything. Trust me, if you want a on the rise popular fic make a nice cover or make someone else do it for you. There are a lot of cover shop's out there. Or make your own like me. Like once I changed the NOTORIOUS cover and I attracted a lot more readers even though I already had a lot.

→ Be experienced, read fanfics and know what you and other people fangirl too. Then apply that something into your books. Since I am a giant ass fangirl and I belong to many fandoms I have a good idea of what people fangirl too, and appeal to your many readers. There could be casual readers or weird ass fangirls. Appeal to the many kinds.

→ Development is very important. Yet it lacks in some fanfic and ruins the story. Seriously I hate it when I read a fanfic and bam they are having sex on the 4th chapter. Allow time and chapters to build up the development, that allows the readers to build up a connection too.

→ Decent grammar, spelling and descriptions. I am not too focused on this myself incorporating this into my books as long as the readers get what I am trying to say. BUT, please have DECENT grammar and spelling, having too many errors can be very annoying and difficult to read which lessens the readers flow.

→ DO NOT. DO NOT. Make them a girlfriend and boyfriend or kiss in the early chapters. Why? Well isn't that what shippers are looking for? Once they become an item, the shippers mission is complete and some lose interest.
MYSTERIOUS SPOILERS. IF YOU DON'T WANT TO BE SPOILED LOOK FOR THE STAR AT THE END
In MYSTERIOUS I made them a couple in the last 10 chapters I think. And most of the readers don't leave because they developed an attachment people that have read that far, I know have been following this book as a loyal reader. So they must have developed some type of attachment, so they will probably reading to the end for that sake of closure.

★

→ Clean layout. You know what I find refreshing to read? Clean layouts on a fanfic. Clean layouts are evenly spaced, paragraphed, a new line when a new character is talking. I don't want to read a chaotic fanfic where you are confused on which character is talking. So please.

→ ORIGINALITY. Okay to be completely honest, some jelsa fanfics can be the same plot but juggled around but with the same moments and things like that. And if you are a reader of many jelsa fanfics you would know that the amount of jelsa school fanfics that are basically the same. For example there is a lack of plot and story, it doesn't have that much direction.
It's just: Jack and Elsa are in school will love bloom?
It's basically the same dramas, and if you read many jelsa school fanfics like that you can predict what can happen.
I probably sound rude in your head but it's the truth we are lacking originality! But I am satisfied because a lot of fics are becoming more original.
And an original story is probably going to be the star of your fic trust me. It's a pillar to a great fic that everyone will love.

→ LASTLY, when making your fic and you are just about to publish it. Think. Think if you really want to commit to this and make more chapters and make it to the end.
Don't be mean and just stop updating it's kind of upsetting to the readers. So just take a minute.
I have learnt my lesson. That's why I carefully work on new books and I haven't published anything yet.

Okay, I'm done. I may put up more sensei chappies but that's generally what I wanted to show you.