Every post should have a question – this encourages comments!
Every post should also ask users to save and share – but think of creative ways to do this rather than just begging for the share/saves. You want to earn the share/save from them 🙂
If you are on Instagram then stories are probably the best way – the only downside is that I find fewer people see my stories see my feed post. However, feed posts are kinda static so it is hard to do much with them unless you ask questions.
Stories mean you can use all the range of features, e.g. DM, Poll etc