I host my comic on Tapas and Webtoons, I also host it on my own website as well.
Initially I got some people on discord and some loyal followers on other websites to subscribe to my story on either Tapas or Webtoons. which got me around 25 subs on both to start with. From there it stagnated. Been a year now and I've only gotten 70 subs on Tapas, but recently I got promoted on Webtoons and gained over 500 subscribers there. I have no way of tracking my readers on my website so the site it less prioritized than Tapas and Webtoons but I still have my comic there in case things change. Anyway, I had been experiencing burn out since 6-7 months ago so I haven't been promoting my comic as much as I used to, I'm just kind of going with the flow of things. If I get promoted again by Tapas/Webtoons then that's good, if not that's okay too.
In conclusion, I'd say I have no idea where most of my readers come from but what I do know is I have some funny readers, they make me want to keep drawing my comic even when I feel like my story isn't worth their time. At the very least I have people who want to see the story till the very end. : )