Here I want to touch on two joints, and two joint positions.
Shoulder and Hip Internal and External rotation. It will be important to learn about your body, and learn how to initiate movements specific to the areas you're trying to work. Rotation will be a huge emphasis, especially for the hips and shoulders. Rotation is the fundamental motion of those joints. Meaning the better rotational mobility you have, the better global mobility you will have as well.
Take a look at the video and try to perform the movements to get a good feel for creating rotation at those two joints. This will help come class time.