What I did in 2018 was

1. picked an instance where the local timeline looked interesting/relevant to some of my personal interests
2. looked through there and also #hashtags for my interests
3. through those avenues, followed everybody who looked remotely interesting at all! With the understanding that I was going to start big and some of those people probably wouldn't accept my follow, and some of them probably wouldn't turn out to be interesting to me/compatible in the end so I would remove my follow.

I feel like casting a wide net and filtering down to match your own taste and the kind of people you want to meet is a good way to start curating the Mastodon you personally want to see, since an algorithm isn't going to do it for you. It takes time but is rewarding in the end. With Masto in specific, most instances by now have upgraded software to the point where migration tools are available, so if you end up not even liking your local timeline you can take all your followers, follows, blocks etc and just try someplace else.

You could probably also use lists to help with this process somehow but I never really understood them either here or on Twitter lol.