A few recommendations for life on Mastodon:

1) Follow anyone you think looks potentially interesting; you can always unfollow later, and they may lead you to new people via boosted posts.

2) Boost posts you think are worthy, so others can discover new content.

3) Don't obsess on replicating your Twitter follows on Mastodon; let it be its own experience, and grow it organically. Obvs follow anyone you miss from Twitter, but this isn't a 1:1 replacement; have fun, follow your instincts.