No one really how the Instagram algorithm works but it's common knowledge that if you interact with other accounts this will boost your followers and likes because more people will find your profile. These are the simple things you can do that are considered "engaging with other accounts":
- Follow new people, unfollowing & refollowing the same account won't work
- Like someone's post
- Comment on someone's post
Trick to get more likes
All you need to do is just engaging with other accounts a lot more than you usually do right before uploading a new photo or video, this way your post will get all the attention it deserves. Another way to increase your engagement is by creating a custom hashtag.