I believe it is important to establish an interactive relationship with each individual student. This will get them to buy in. I think its important for the student to know that your invested in their success as well.

It is important to give good meaningful feedback to students in discussion boards and the like. However being careful not to take over the discussion. You don't want to spoon feed answers to students if they are supposed to be thinking for themselves? If they seem not to be on the right track about a topic, that will lead me to ask a question  designed to get them back on track.

I have learned that maintaining structure that is easy for the students to understand and follow will help keep the students engaged. This helps with retention. Also making it easy for students to track their progress and communicate with the instructor is very important.