6. Provide the opportunity to grade comments
Several media outlets have found it useful to allow their commenters to grade posts.
Of course, this is not an infallible method in prioritising or grading comments on a scale of constructiveness, but it is worth an attempt.
Inviting commenters to pay attention to posts they find valuable, rather than those they disagree the most with or find offensive may contribute to improving the discussion. This can be combined with rewarding commenters who follow the rules with greater visibility.