Communications policy in your syllabus: establish a policy of how you will communicate with your students and stick to it. How should students contact you and how quickly will you respond? How will office hours go?
Overview Announcements: Every week, send students an "overview" (e.g. via Bb announcement tool) that tells them what’s due and what the daily activities will be. See instructions for lecture-based and seminar-style sessions.
Weekly wrap-ups of course activities/performance: use the discussion forum, announcement, or email tool to deliver a weekly wrap up in a conversational tone, that lets students know, generally, where things are and how well they are going - you can choose to create short videos to do the wrap-ups to create a greater sense of your presence in the virtual classroom.
Provide a space for ongoing communication with the whole class: This can be a discussion board for Q&A, or if you prefer something less formal, you can create a WhatsApp group or Slack. This will save you a lot of emails asking the same question. It can also help build community - see the section on Knowing Students and Building Community