Thanks to Steve Rubel for pointing out Lifehack.org's useful guide to Commenting Tips.
Back in 1999, Shel Horowitz pointed out The Marketing Power of Discussion Lists. But, as discussion groups slowly go the way of Usenet newsgroups, comments on key blogs have become the new way of joining the conversation. (See, Maggie? I did call it a "conversation"!) But, like joining any club, it pays to know the rules.