General expectations for an online instructor
Most course materials should be in place before the course begins. Online students start panicking if they haven't heard anything about the course by roughly a week before the course begins, and when they log in they expect to see a full course, not an empty shell. In addition, having course materials in place before the course begins avoids nasty surprises when that video just refuses to upload for you.
Of course, having the materials in place does not mean that all the materials are visible to the students. It would be silly, for example, to have timed exams accessible before they are actually administered. Nor does having all the materials in place mean that you can't edit them later, as you interact with the class and get ideas for improvements. You do, however, need a full, solid draft of the course in place before you start it.
Make sure students know how to contact you. Nothing promotes student panic more effectively than the instructor being unavailable. Put your contact info—minimally, a working email address and a working phone number—in your Moodle profile and on your syllabus. This does not mean that you have to answer either your phone or your email at unreasonable hours, but you do need to be reachable.
If you're going to be unavailable for some time during the course (for example, if you're traveling during the course and will be unavailable while you fly), make sure students know well in advance when you'll be unavailable and when you'll be available again.
Put a photograph of yourself in your profile. From the students' point of view, it gives you a face.
While the course runs, have scheduled online times at least as often as you'd expect to meet the students face-to-face. In a short-format course like a summer course, this might mean every weekday. In a longer-format course offered over a full semester, it's more likely to mean a few times each week. You're going to need to spend a significant amount of time on the course anyway: answering emails, grading assignments, participating in discussions, and so on. If you do this at a scheduled time, and tell the students your schedule, it becomes like an online office hour. The effect is that you are much more accessible (from the students' point of view) than you would be spending the same number of hours online but not telling them when. Furthermore, it will be far less anxiety-inducing for students who try to contact you outside your scheduled online times and don't get a quick answer—since they know when they can reach you, it won't bother them so much if they can't.
Do your grading in timely fashion, and make sure you post the grades where students can see them. Because online students don't have as much feedback from direct interaction with their classmates as face-to-face students, it's even more important to keep your grading up to date when teaching online. In addition, keeping students abreast of how they are doing in the course helps keep students engaged.