Some suggestions (in no particular order!)

What have I forgotten / got wrong? Please share your suggestions in the comments.

1. Make sure your Instagram handle and Twitter handle are the same
2. Give some thought to writing a pithy, useful profile Bio
3. Set up www.linktr.ee to keep your links up to date. You cannot post links in Instagram which is annoying. So you have to always say ‘Link in Bio’
4. Set this up so that your Instagram images show up properly on Twitter – https://ifttt.com/applets/103249p-tweet-your-instagrams-as-native-photos-on-twitter
5. Video is extremely effective. Gets great engagement
6. If your videos have speaking in them, make the effort to add subtitles
7. Use hashtags to grow your audience. But beware that too many looks spammy. Look at people similar to you on Instagram to get a feel for useful hashtags
8. Get involved! Follow a load of people similar to you and begin commenting usefully on their posts. Helping people and answering questions is the best way to grow a useful online audience
9. Image quality is even more important on Instagram than elsewhere online. Make your images bright and as good as possible. Use Snapseed (or similar) to edit your pictures before posting
10. Don’t get lured into posting endless beautiful but bland images. Be original. Be yourself. See https://www.instagram.com/insta_repeat/ as an example of how beautiful does not always equal interesting
11. Instagram Stories are massively popular at the moment. See them as fresh, quick, timely ways to give an authentic glimpse behind the scenes. (Or see them as the next phase in our insatiable race to the bottom of attention deficit and quantity over quality!)
12. #throwbackthursday #tbt is a useful excuse for rehashing good but old content on Thursdays!
13. ‘Later’ is a useful app for scheduling Instagram posts if you want to have an actual life as well as posting regular, timely online content
14. ‘Repost’ is a good app for generating extra content, promoting people you support, building your audience, and becoming an authority in your niche
15. Make the text for each picture interesting. People neglect the impact that good writing has on Instagram.
16. Ask questions. Social media is really useful when you ask specific, actionable questions of your audience. They can be questions that will help you learn, or direct asks like, “We’re trying to grow our audience here, please will you tag the name of any friends who might enjoy following us”
17. Create posts about the ways that influential people in your niche are making an excellent ruckus. Praise them, promote them, distil their wisdom. This helps them. It helps your audience. (It also – perhaps – will help you if you tag that person’s name and pique their interest in your work)
18. Try to post regularly. It’s better to post once a week on for a year than to post 52 pictures on a single day. A few times a week is best for the algorithms, but that might not work for you
19. Ask people in a similar niche to post about your work. Return the favour. Remember that social media is not a zero sum game! Help other people
20. Reply to people’s comments and answer their questions
21. Entertain, educate or inform: that should be your goal with each post. If it doesn’t accomplish one of those consider not posting it
22. Selfies or showing off quickly gets boring
23. This blog post has a load of info about using social media in general – https://alastairhumphreys.com/social-media-advice/