When you're choosing what to put online, focus on your essential learning objectives. Especially at first, keep your course as simple as possible.
Remember that not all your students have fast internet at home: try not to post long videos or require video chat. Providing text options helps reduce data speed requirements and also has the benefit of enhancing accessibility.
Communicate often and clearly with your students. For example, there's an "announcements" tool in Blackboard you can use to spotlight/repeat important information.
It's best to compose in MS Word or wherever you normally do, then either copy+paste or upload the file to Blackboard when you're done. (In other words,don’t use Blackboard as a word processor. For security reasons, it "times out" when it thinks you may have walked away from your computer, and that can cause you to lose work.)
When you create a new item, don't alter any settings you don't have to--especially do not touch the "adaptive release" settings.