I think having an open conversation and being able to set clear expectations is crucial for students taking online classes.   Also clearly outlining what your role will be in the class is important too.   

I think it is important to assess student's basic technology understanding and abilities.  This lesson talks about asychronous learning and sychronous learning.  Knowing what infomation would be better taught sychronously vs asychronous I think would be critical for the success of the class.  There are many tools a teacher can use being familiar with them and knowing the capabilities and understanding of your students is important.

Communication is very important, but it is especially important when teaching an online class.  Being able to articulate your lesson in a concise easy to follow manner is very benefical to the students learning enviornment.  I think it is also important to be able to post questions and answers in a place where all students and the teacher are able to access the page easily.  This is what I would do if I were to teach a math class.