First, it's important to find an instance that caters to your interests, especially if you have more niche hobbies. Once you're set up, search for and follow hashtags related to your personal interests, and use those to find accounts you like. Use hashtags in your own posts so that people can discover you more easily, and browse users that follow you to see if they'd be interesting to follow back and expand your network out. Keep an eye on the local and federated timeline for interesting posts, which includes all posts from people on the same instance and from all federated instances. Eventually, as you build up a follow list (and especially as you follow highly active accounts) your followed accounts will start introducing you to new accounts themselves through boosting posts.

It's more work since you're building the network yourself instead of having it spoon-fed to you by an algorithm, but it's overall much more rewarding, and lets you tailor your experience to your own personal preferences.