My weekly promo routine involves posting to Instagram, Twitter, & Facebook. I create promotional images out of the episode thumbnail like this:
And then slap the page on too with links to tapas/webtoons and call it good.
I used to hit Reddit as well, but stopped because r/comics and r/webcomics aren't great places for long-form stories, and I haven't yet found a better specialized sub to try lol
The other 3 platforms work pretty well. Instagram is the best, I'm always seeing new people find and like my stuff through hashtags (even if they don't end up following or wev). Facebook I use an artist page but have decent reach to people I know irl. I've gotten kickstarter backers and a couple of commissions this way. And twitter is... not as great for me, but easy enough to be worth~