One of Chait’s:
Don’t debate straw men. If you’re arguing against an idea, you need to accurately describe the people who hold them. If at all possible, link to them and quote their argument. This is a discipline that forces opinion writers to prove that they’re debating an idea somebody actually holds. And quoting the subject forces them to show that somebody influential holds it — if the best example of the opposing view is a random blog comment, then you’re exposing the fact that you’re arguing against an idea nobody of any stature shares. This ought to be an easy and universal guideline, but in reality, it’s mostly flouted.
TNC seconds him:
This is not only for the benefit of people who read you, but for your own. To paraphrase Douglass, a writer is worked on by what she works on. If you spend your time raging at the weakest arguments, or your most hysterical opponents, expect your own intellect to suffer. The intellect is a muscle; it must be exercised. There are cases in which people of great influence say stupid things and thus must be taken on. (See Chait on George Will’s disgraceful lying about climate change.) But you should keep your feuds with Michelle Malkin to a minimum.
The Dish 