How to get followers on Mastodon
Fill out your profile: Tell about yourself and your interest. Use hash tags. Header and profile pictures are also very appreciated.
Follow others: First browse through the local timeline where you’ll likely find the most interesting content and people to follow. Follow them.
Follow others, Part 2: Visit the profiles of the people you follow. There you see who is following them and who they follow.
Like or boost generously: a “Favourite” means: “I’ve read your post, I find it interesting” and notifies the poster about it. A “Boost” means that the post will appear in the Timeline of your followers and in the local Timeline. It also shows the poster your support and interest in the topic. Follow people with interesting posts and you’ll likely be followed back (if you have filled out your profile).
Comment on posts: Show your interest or add interesting context by commenting on posts. Tell about your experience. Did you find something interesting or are you curious? Reply with a comment!
Create or share your own content: The Fediverse is not Twitter. You are allowed to post about mundane activities. Share your thoughts. There are no Quote posts, people will not ridicule you. The Fediverse is overall a much friendlier place and tolerance for hate is very low.
Conclusion: Be patient. In the Fediverse there are no algorithms. Your followership will grow only organically. It is a two-way street. The more you do and get involved, the more people will take notice. That’s the beauty of the Fediverse.