I like this point. I would add to it one preceding step: Make sure I have not simply misunderstood my debate opponent's point.
If I say "your post doesn't make sense", that's a clear challenge. But, if I phrase it as, "can I rephrase what I think you said", that's a lot less likely to generate hostility, both in me and in my opponent. Plus, I might learn a thing or two.
I also like the idea of avoiding (like the plague) using the word "you" when responding in a debate. The word is perfectly valid, but when it is used, it tends to set up a wall between us. "Your ship design is no good." is a lot more threatening and challenging than "if I understand the design, I'm not in favor of it at all" or even "I don't like that design". Focus the negative on myself.
NOTE: When I say "you", I mean "you plus all its variations".
