Getting attention on social media and getting attention on Tapas are quite different things in my experience.
On social media, people like content that's easy to share. Keep it as divorced from wider continuity as possible, and share panels, jokes, illos and memes that are easy to consume without deeper knowledge of your story and characters. It's a totally valid tactic to promote based on what archetypes are in your series, or what identities it showcases. Got a comic about a gay autistic person? Get on those hashtags. You're a south asian creator? Get on those hashtags. People tend to curate what they share on social media based on the identity they want to project, or things they think their followers will react to, so you have to play to that.
On Tapas, it's about an engaging reader experience, and a sense of connection to your work and community around people following it. You want polished presentation, a regular update schedule and strong characters. Make sure every update has something that a person could comment on, like a character moment, plot reveal, a joke, something sexy, something scary, something relateable etc. Then try to respond to comments as much as you can. Say something funny in your creator comments under the page to encourage a casual vibe where people can be silly; it helps!
Generally on both, try to seek connections with other creators. Offer help and advice, or feedback, draw people fanart, give out genuine compliments and tell people "well done!" for hitting milestones. It's incredible how many people undermine themselves by being mean and bitter to popular creators because they're jealous, when if they were just nice to them, recognised the common humanity, and how lonely comics can be when a person is making them to a high level of polish, they'd be making friends in high places that might some day help them out.