I was looking up Arne Næss, a Norwegian philosopher and environmental campaigner for another post and came across a set of 'rules' he formulated to ensure fair and objective discussion. They will all be familiar with anyone interested in philosophy, rhetoric and argument, but I see them being broken so often (often by myself, to my shame), that I thought they were worth repeating.
1. Avoid tendentious irrelevance
Examples: Personal attacks, claims of opponents' motivation, explaining reasons for an argument.
2. Avoid tendentious quoting
Quotes should not be edited regarding the subject of the debate.
3. Avoid tendentious ambiguity
Ambiguity can be exploited to support criticism.
4. Avoid tendentious use of straw men
Assigning views to the opponent that he or she does not hold.
5. Avoid tendentious statements of fact
Information put forward should never be untrue or incomplete, and one should not withhold relevant information.
6. Avoid tendentious tone of presentation
Examples: irony, sarcasm, pejoratives, exaggeration, subtle (or open) threats.