More tips:
1. Find your tribe. That's your fans. That's the whole point of social media. There's no point being followed by people who don't care about what you're doing. You need to find the folks who will read your stuff and support you, buy merch, follow you on Patreon, YouTube, whatever. Raw numbers are better than nothing, and they definitely get the ball rolling as far as credibility goes, but a curated list of followers is the goal. Find your tribe.
2. Review/comment on books, movies, television/streaming shows, etc. in your genre, adjacent genres and stories with similar characters or situations (for example, anti-heroes or empowerment stories or whatever), including cool YouTube content - on as many platforms as you have time for. Remember to share and tag all of your posts and content across the platforms you participate on. Make it easy for your tribe to find you.
ALWAYS be positive in your reviews/comments. It's a short form format so pick something super cool, character, plot (no spoilers), crazy scene or idea and briefly say just how super cool it is. Video memes work well too, as long as they are either super inciteful or funny. Posts with videos get shared way way more often.
ALWAYS tag the author, their publisher (if they have one) and any group that might enjoy the comment, including your own groups, such as facebook groups, the streaming network, blogs on the subject. Tag as many core folks as makes sense without being goofy about it. Keep a list.
3. NEVER be political or religious. Let your books speak for you. Just steer clear - way way clear. No, even further...further...yeah, over there. Actually, um...take another step back just for good measure.
4. If you do video posts, like YouTube content, talk about the gear you use, cameras, lenses, etc. Talk about the software you use for writing, for covers. Talk about your process, the designers you use, cover artists, book services, etc. - in both writing AND with your social media content. Tag everyone related to what you're talking about. Posts with video get shared way way more often.
5. ALWAYS stay on brand. This is your opportunity to present yourself exactly how you want the market - your fans - to see you, it's like a perpetual first date. Be on your best behavior - fly casual! Posts with videos get shared way way more often.
6. Talk about products that relate to what you're writing or that you stand behind - but don't violate # 3 above. Keep it short and remember to tag the company and any group that might find the post useful. Posts with videos get shared way way more often.
7. ALWAYS be authentic. So, if don't have something nice to say, don't lie, just find another discussion. Don't be duplicitous, or sneaky, be above suspicion. Be as transparent as possible - but keep your private life out of it.
8. ALWAYS appear to be living your best life. Keep complaining to a minimum. It's fine to talk about how the tree fell on your house, but finish it up with how amazing the contractors and services were - even if they weren't. Remember to tag all of them. Be on your best behavior. It's like driving a company car with the name on the side. Oh, I almost forgot, posts with videos get shared way way more often.
9. ALWAYS be active. Share other posts and content regularly. Participate. Pay it forward. And tag everyone that needs tagging.
10. Posts with videos get shared way way more often.
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eta: Promote other folks more than you promote your own work, by a lot - at least 80%-20%. Your tribe will figure it out and they'll ask what you're working on, when you're publishing, etc. At the end of the day, you want your tribe to engage with you. They're your fans. Think of the stuff you're a fan of and how much you promote those products and services just because you like them. And that's the end game. Every fan is a market vector - and they're excited about it.
It's better to post snippets of your work than to push the books themselves. Allowing fans to look over your shoulder is a proven strategy.
Advertisements are fine, just keep them separate from your regular participation.