There are a lot of effective ways of debating. The most important is being well-written with plenty of reasoned responses backed up with corroborating sources. The "most effective" I would think is a bit subjective to style and content. I have some posters in mind, but that might be geared towards my personal preferences.
I'll also echo Coyote's sentiments. Some people tend to belabor their points and so I don't even bother reading it if it goes on endlessly. It may be well written but I don't want to read a book or a dissertation. I just want to hear what you have to say. Get the point across quickly and succinctly the first time and you won't have to repeat yourself 10 times on the same post.
"Men never do evil so completely and cheerfully as when they do it from mistaken conviction." — Blaise Pascal
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