I would like to also point out that a lot of people who gain their subs (wherever they create BL content, Romance, or otherwise) had been working on their content for a long time. Sometimes, it does feel like some creators get a lot of subs overnight. But we also have to remember that:
A) A lot of creators have already been stationed on other sites. Webtoons, Smackjeeves, even Deviantart, and they just might now be making their way over to Tapas. To which, my advice would be to post your comic in more than one place. It doesn't hurt to test out each site to see what it would offer.
B) A lot of creators have also posted content outside of their comics. They might post sneak-peeks, concept art, notes, sketches. They might've even done commissions before comics. That way, they've built an audience that likes their work and kinda pointed them in the right direction. So I guess another suggestion would be to showcase your work -- post more work that might not have to do with your comic. Just so people know that you are capable of creating more content in different ways.
C) A lot of creators also worked with other creators. They'v given feedback, maybe worked in a collab with someone they know (and not a total stranger), etc. They might've also posted more information for things other than their comic on their social media. So it's not just "update, update, update". One thing you can do is work with other creators to give and receive experience. See what others have to offer in terms of advice, but also be willing to help them as well.
We just gotta take it one step at a time. After all, subs can take a wee while to come in.