Meetings with teachers are often either very awkward or just quite nice and even sociable. Actually, the same goes for online meetings, at least in my experience. Some useful tips are:
Prepare your questions or something you want to discuss extra well and write it down
When preparing well for the meeting and write down, it becomes more fluent and less awkward, as silences are avoided.
Make sure your WIFI works well
When meeting with the teacher it is even more important that your WIFI goes well, also to make the conversation more fluent and less awkward, and moreover, of higher quality. If necessary, use your hotspot of your phone. Or use the chatbox if it really does not work.
Act like it starts 10 to 5 minutes earlier
Suppose the meeting is scheduled at 10.00, act like it is scheduled at 9.50 or 9.55. Getting late is definitely something you do not want, so this is a good way to avoid this.
Do not led awkwardness stand in the way of asking questions.
Most students probably have experienced the following most awkward moments, namely that the teacher asks if anyone has a question on whatever platform you are using, and everyone remains silent (also awkward in real life). But do not led the awkwardness of asking questions online (and physically) prevent you from actually doing it.
Avoid eating / being too comfortable in general
Of course, there is not wrong with being comfortable, this is actually good. However, act like you would do in a normal meeting, where you probably would not eat or sit slumped.
Be (extra) careful in (not) interrupting
As you and your teacher are not face-to-face and the quality of the video and/or sounds are not always that good, it becomes more easily to interrupt each other, which you want to avoid.
Download the free pdf guide on how to successfully studying from home during COVID-19.