well you just promote your stories you know. If you have more then one story you're writing (like I do) you promote it in your own story so readers know. You can promote on Tumbr, Instagram, and twitter too. (I usually promote mine on twitter)so yeah.

A lot of people self-promote their stories by visiting others' profiles by leaving a comment on their wall suggesting to read their fanfic. Or they even send messages to other people asking to read it.

I agree. More commentors are better than having more subscribers, although subscribers earn you more karma points.

It honestly helps to write a story with a love interest who is popular on AFF. Most people won't read a fic unless the love interest is somewhat on their bias list. Also stories accumulate subscribers over time. I know that starting out at a writer can be pretty rough on this site, but eventually, even time itself will bring subscribers so don't feel too discouraged. :/
I can say that I honestly remember being so happy when I reached 300 total subscribers and now I have more than 10 times the amount after a year or so.
The other people on here also gave good advice! Attractive forwards, catchy titles, let them know your story is worth reading from the start. Good luck! :)

honestly, i dont know how to get them either. they just subscribe ㅋㅋㅋ and it isn't really about the number of your subscribers. sometimes, they subscribe and dont comment at all. i checked your stories just now and saw that they are all 'subbers only'. sometimes readers tend to shy away from it when they see that tag. of course it's better for them to see the content of your story for them to be able to scrutinize it without getting cut off before they subscribe. or some would end up subscribing and when they dont find it interesting, they unsubscribe. another is posting an obvious summary. sometimes readers only have to read through summaries and decide whether they like it or not. sometimes it's better if you use excerpts instead of summaries. it would seem more intriguing if people who come across your fics do not know what they're in for. describing your characters ahead of time is also a no no. good readers would like to get to know the characters through the story and not through a predescription. it would be easier too because your subbers wont expect anything in case you wish to suddenly give a twist to the characters' persona and if there are surprise characters, a list of it isnt really gonna make it 'surprise'. a list of the main characters would be fine without too much details is fine. summaries should be vague and shouldnt give out too many details and try to develop a plot with a lot of twists. they're exciting and interesting. dont invest everything on the foreword even if it's the first thing people see. sometimes those stories with lesser visuals and give-aways are the best. hope this helps ^^

People talk a lot about comments, and I agree - I'd rather have 10 regular commenters than 100 subscribers... but a lot of readers are also "silent" readers, who just aren't comfortable commenting...

Anyway, back to your question. There are actually several ways how you can get subbies. First thing you can do is, of course, make your title and description interesting. Second, you need some nice graphics. A lot of people won't even bother giving your story a try if they don't see a poster. That's a very sad reality. But I don't think you have a problem with neither of these.

Setting your stories on "subscribers only" is a double-edged sword. I learned the hard way. Yes, people will subscribe to your story to check it out, but not everyone does. Some people won't read the story BECAUSE it is subscribers only. The common logic is "why subscribe to something that I don't even know if it's good or not?" And, some of the people who subscribe might find the story not to their taste, but they won't unsubscribe, which gives you a false impression of how popular your story actually is. I still have dozens, if not hundreds of subscribers whom I know for sure don't read my stories.

I'll continue in the reply section, since it's getting a little long...

Feedback from subbies is important. As the story get more interesting, i believe the story will gain subbies. And yeah, first chapter is important. Sometimes i felt like giving up, but just keep on like nothings happened.

Just write an interesting story..

I agree. I think it's better to have more comments that subscribers since feedback is more important. You can use it to further improve your stories and it really is important to know what the readers have to say about your fanfic. :P

regarding what you said about all writers want more subs...well not really...i'd rather have commenters than subs even though subs provide me karma point...lol. i'm just sick of the lack of feedbacks. even if i have subs, i don't even know if they're reading or not...i don't have any suggestion to offer for now though...sorry. good luck on getting more subs though