I don't use social media aside from reddit (if it counts!? it really feels more like a forum than a proper social media site). I couldn't really get my art out there no matter how long and how hard I tried, and there's just too much meaningless noise on social media. Also instagram insisted on showing me gross videos.
I run two comics: Bestia's Wrath (a Star Wars the old republic fancomic about a sort of a canon character stand-in), and The Lost Firstborn (an origin story of my DC Comics \ New Gods OC). I kinda got 30 subs on the latter recently and I think it has to do with the fact that The Lost Firstborn updates twice a week while Bestia's Wrath has 1 update a week. Someone here on the forums mentioned that comics that have shorter but more frequent updates tends to be picked for featured and are also on the recently updated page.
And also TLF is probably easier to follow fandom-blind because it's a fairly straightforward origin story comic about an OC while Bestia's Wrath proooobably is better enjoyed if a reader at least knows the basics of Star Wars or played SWTOR so its a bit less accessible I guess.
I did post a link to Bestia's Wrath on the game's subreddit but I'm not sure if it gave me a lot of exposure. I might post a link to The Lost Firstborn on a DC comics subreddit of some kind at some point but I think it's doing pretty well on its own.
I also participate here on the forums, and while I actually don't plug my links that often, I think participating also helped because being friendly kinda goes a long way and there's also a link to my comics in my profile here so someone checking it out might click on them. There's also a thread where you can plug your updates whenever they happen, and it brings some readers in I think. Not that many in my case, but it does. There's also many threads where you can promote your comics, although I think they get closed once in a while.