I will preface this with the fact that no one's journey is going to be the same and all I can do is offer advice and what has worked for me. Take everything as such, and not hard and fast rules to success. Cool? Cool!
First things first, hi, I'm Lacey, I make the comic Lies Within. It's currently not updating on platforms, but it went strong for 3 years on both Tapas and Webtoon and gained ~30k subscribers on each. I was inspired by the recent post "If you want to be popular, do this" to make this in earnest, because I think some of my marketing tips can actually be useful to others. I'll do my best, anyway!
Make good work. This one's a no-brainer but I felt I needed to stick it here. Your first attempt won't be your best. Spike Trotman of Iron Circus once said you're going to make ~200 bad comic pages before you make good ones (paraphrased, but you get the point). Sure, certain genres like Romance have more popular comics, but they have more comics overall. No one genre is a free ticket to popularity, but the good news is that even the most over-done and popular tropes can be interesting depending on who's re-telling them. You've gotta have a compelling story first.
Pick a regular update schedule and stick to it. This could be twice a week, once a week, once every 2 weeks--just pick a frequency and a day and be reliable. If you can't make an update or need a hiatus, make a post to let your readers know. (I tend to delete these posts later, as they interrupt reading for future readers.) I wouldn't say treat it like a job (unless that's what you want to do)--more like a social commitment.
Know your audience. This can be hard but I get most of my info from context clues in the comments section, but we also tend to make stories for specific groups of people. Is your audience mostly teens? Adults? A mix? Do they prefer reading vertical scroll comics on apps, or do they like going to a personal website where pages are set up in print format? Having an idea as to who your comic is for is important when it comes to knowing where and how to promote it.
Advertise smart. (This is gonna be a long one) Casting a wide net and linking your comic all over a creator forum is fine, but where are your readers most likely to be? Let me break down my marketing strategies for the spots on the internet where I advertise my comic. For reference, my audience is a bit of a mix but skews young.
"So what do I post?"
Obviously, comic update posts. That's the first one. On your update day, post a "hey! I updated! heres a link!" with an image of a crop of the page, or your comics logo, or a mixture of both. If you only update once a week, consider making a new post a few days later with a different crop. Keep it fresh!
Also! Take a page out of the books of most popular comic creators on social media. Check, Please! and Griefer Belt have entire accounts dedicated to characters speaking in-character; Long Exposure's creator made mini comics/drawings with their comic characters before launching their comic and they're doing it again for their next project. Draw your characters into popular memes. Allow people to relate to your characters in context they already know, and they'll care about them!
Twitter - Twitter is a great creator hub. There are hashtag events, webcomic discussions (webcomic chat), and accounts specifically made to retweet webcomic updates (webcomicupdates, webcomiclibrary). Engage with your fellow creators. Get excited about and share their work, and you'll find people that get excited about and share your work in return. Most of my readers from twitter make webcomics themselves. It's fun to read and geek out over each others work!
Instagram - Instagram can be a great tool if you take advantage of popular tags. Sure, you can use webcomic, comic, comicupdate, etc etc--but think outside the box, too. Is your style manga-esque? Use the manga tag. Is it full of monsters? Vampire, supernatural, monster, etc. People follow tags on instagram, branch out and find some readers.
TikTok - I don't know how long this advice will be viable to US-based folks and non-US folks once the app goes poof (if that's still happening? I don't know). I've found some success in TikTok, they love Webtoon over there. So much, I usually get asked what my "webtoon" is called. My most popular TikToks tend to be comic-style videos, where characters talk to each other in speech bubbles or voiceovers. Once more, go forth and meme your webcomic characters!
Tapas - Your cover page is your comic's biggest advertisement! It's your hard work, at a glance! Tapas recently made them nice and big, which I absolutely love. Make sure your comic's title is easy to read, and that your cover image is interesting and alluring to new readers (without being a lie, haha, don't go making a Romance cover for an action series?). Second, is your comic's genre reflective of your comic's content? And are you making the most out of your genre? I would describe Lies Within as a drama with an LGBTQ+ cast, and when I got an email about tapas adding the LGBTQ+ section, I took the opportunity to make that its primary genre. I believe there was a form to fill out right before the genre went live, and I filled it out and was picked in a LGBTQ+ collection. As long as my comic was updating, I was near the top of the category and that gave me a huge boost every week. I digress. Make genres work for you.
I wish I had hard and fast rules about how to make trending, but I try to line up my updates with my social media announcements about the update to drive as many people to the update at once as possible. I also left questions on SM, and asked folks to like and comment on the update comment. I nearly always got on trending on update days.
Cross-Platform - Are you only posting on tapas, or only on webtoon? What's the reason for that? Is it time? That's fair! But understand there are unique audiences to each platform and posting in more than one place is an opportunity for more eyes on your work.
I hope this helps in some way. It's not quite 8:30am and I feel like I've rambled on long enough! If you have anything to add from your own experiences, please feel free!
Edit: One more thing! I touched on this earlier re: popular creators, but you should absolutely be watching folks who have "made it", or are doing well. While it's true everyone's journey is different, it doesn't hurt to learn from other creators!
Find your "mentors". Check out the staff picks section. Check out the popular (free-to-read, so there's no advertising advantage) comics in your genre. Look at the covers, read the synopsis. Read the comic! Why does their work stand out? What are they doing different? Do they have social media? What are they doing over there? Learn from successful people. Don't DM them asking for free advice, but just observe, follow and learn.