The ultimate technical goal for the instructor is to make the technology transparent. When this is done, the learner may concentrate on the academic task at hand.
Before generalizing to the conference about a contribution, consider such things as the tone and content of the posting, the author and his/her skills, knowledge and attitudes that you may know about from prior conference postings, and time of the posting in relation to the conference thread.
Summarize the assigned readings online so that the discussion in the CC remains mostly self-contained.
Experience strongly suggests that a long, elaborate, logically coherent sequence of comments yields silence. Instead, use open-ended remarks, examples, and weaving to elicit comment and other views.
Praise and Model the Discussant Behavior You Seek.
Do Not Ignore Bad Discussant Behavior. Request change (privately)
Avoid Lecturing. Single contributions should be limited to no more than two screens.
Distance learners have lots of questions and need feedback and reassurance. If these are missing, you can count on lukewarm participation and course dropouts
Develop a learner-support structure. Supporting DL participants is work-intensive. Be prepared to answer these questions: 1. How will they communicate with the trainer? 2. How will they communicate with each other? 3. Who will answer their technical questions? 4. Who will answer their subject matter questions? 5. Who will grade assignments and evaluations? 6. Who's in charge of feedback?
Have an introductory course for novices. You can offer new users a brief course that instructs them step-by-step how to use the DL technology. Keep it optional, though.