Fortunately, most of the recent Twitter emigrés have been doing #introduction posts with tags about their interests, which makes them easy to find. Via the internal search, and with sites like https://fediverse.info/explore/people if they register for it.
And people have also been sharing services like
* https://fedifinder.glitch.me/ and https://twitodon.com/ to find people you were following on Twitter, and
* https://fedi.directory/ and https://communitywiki.org/trunk which have users categorized by interests and what they usually post. Just randomly clicking around these exposed me to new areas of interests (eg. generative art) that I had no clue existed on Mastodon. These follows then serve as your gateway into discovering more users, via their boosts (retweets in Twitter parlance).
My timeline is a lot richer than it was even a couple days ago, and it seems this trend of creating external tools to solve Fediverse-wide issues is growing and catching momentum. Which was sorely needed, as it means you don't have to depend on the Mastodon project or instance admins dedicating even more of their time. Instead, the problem gets solved through collaborative effort, as it's meant to be.