I’m admittedly not the best person to talk about it, since I don’t really get the appeal, but in general, Twitter/Mastrodon is for following people you care about. Its largely about people rather than content or discussion, similar to a list of blogs rather than a forum. To find content you can look at tags (mostly to get a general pulse on the topic) but will mostly want to find people to follow, who’s content you want to read, such as friends, politicians, celeberties, or influential figures in your field.

Unfortunately personally, I found no one on Mastrodon that consistantly interested me (beyond a couple bots copying Twitter feeds) but hopefully you’ll have more luck.