You need to use a variety of tools. They should be reviewed to determine which assessment fits the learning you are looking to assess.

Providing the criteria and rubric ahead of time will ensure the students understand what is expected of them. This should be used consistently throughout the term and measure a student's progress.

The way a student is expected to communicate should be clearly explained, demonstrated, and modeled. The communication styles of each generation can be very different, and we cannot expect that they will know how to appropriately communicate in an online course 

Communication expectations are important to define and layout  for students. If you expect something specific of them, this should be laid out and examples given. This is especially important in discussion board communication.

There are so many effective tools. However, each needs to be assessed for the size, type, and specifics of the audience and intent. Tools are not always appropriate for all groups. This needs to be considered and assessed each term. This will help you determine what you should continue to use and what should be adjusted.

Variety of instruction is important. Catering to the different learning styles is essential to student learning. 

I think the most important thing is to evaluate how an activity went. If it did not go well, not assuming it was the students' fault,  but instead to adjust our practice, directions, examples, and learning leading up to that course activity. If you did not get the intended outcomes, adjust.

Consistency is key with online learning. A student needs to understand what is expected of them and to develop a pattern that conforms to the clear expectations of the instructor. This can include the set-up of the course, the submission of DB posts, interaction with peers, how to ask questions, and general expectations.

Finding new and exciting tools is a great thing. However, I think we dive into the use of something that seems "cool" and "engaging" to students without measuring the effectiveness of the tool. For instance, I am using some great Adobe Spark presentations, but I do not have a measurement to say whether a Jpeg of a PP slide that tells them what to do vs a Spark Webpage that looks really professional, is more effective in their learning and the communication of what is due that week. Tools are only as good as their use by the students.