I joined an instance which focuses on the things I'm interested in, and look at the local timeline. That timeline contains original posts (i.e. not replies) posted from that instance. I'd follow pretty much anyone posting anything remotely interesting.

A lot of people tend to boost interesting posts, and following people whose posts gets boosted allows you to grow your follow list with interesting posts.

Unfollowing people that keeps posting uninteresting things is also important of course.