Give students a clear starting point
Provide guidance and feedback
Check-in and get feedback from students
In any class there are considerations about how to open it. You may start with an introduction of yourself, some of the guiding question, or a narrative hook. This is true online as well, though you may have to consider how students recognize the starting point as the starting point. You may want to embed a welcome video at the top of the course page, or perhaps require students to respond to a survey, make an introductory discussion post, or respond to a question before other materials become available.
Giving students a clear starting point is a great way to ease them into an online course.
Create a welcome video for your course and discuss your expectations. Provide your preferences about being contacted, let students know your timeframe for responding emails and how you will conduct office hours. When providing online office hours you may want to use a scheduling tool to make yourself bookable by students. Otherwise you may want to treat an online office like your physical office, being available in there while working on other projects in the event that students do not attend.
Another way to provide feedback, reminders, and guidance is a short re-cap video. Posting a short video where you highlight upcoming due dates, key points, excellent discussion posts, etc. can help show your engagement with the course and let students know that they are having attention paid to their efforts.
Research by John Hattie has shown that feedback and feedback-related strategies are one of the strongest tools for promoting learning in students. If it's good for students doesn't it stand to reason it will be good for teachers too? Aligning your instruction with direction from your learners may further aid their achievement levels.
Instead of waiting for the middle of your semester to offer the first survey, consider having a pre-course survey so that you have something to compare against?
What to include in a student survey