Well, there's people like dons and ibdknox who are famous from their open source contributions who make good comments and are worth following, or those who show up and make worthwhile contributions in their domain space like cynicalkane in finance threads, grellas in law threads, tptacek and daeken in security threads, or garbowza in patents ones. These days some these users don't comment as much however. Mostly it's a matter of lots of lurking until you come to hate the site.

There was/is a chrome extension for following hn users I used a few years ago that was useful, but I haven't bothered to reinstall it after a few OS moves since, mainly because it didn't sync the friends list across computers.