Be More Than Usually Polite

In my blogging class between students in America and Japan, students in America blog in Japanese, and the students in Japan blog in English. In this language exchange between English and Japanese language learners, it is important to make sure that everyone is supportive of each other. Rather than giving students a long list of guidelines for commenting on blog posts, I recommend a very simple commenting rule: "Be more than usually polite".
The complete quote comes from an article by Davis and Thiede on online exchanges, and is as follows:

Be more than usually polite; that is, do not, in your replies to your peers, make any other writers look dumb or wrong or feel bad by appearing to dismiss, disregard, or disparage any statements - or the shape and form of any statements - they have written.

Source:DAVIS, B. & THIEDE, R. 2000. Writing Into Change: Style Shifting in Asynchronous Electronic Discourse. In: WARSCHAUER, M. & KERN, R. (eds.) Network-based Language Teaching: Concepts and Practice. New York: Cambridge University Press.