Shoulders and hips. If I had a dollar for every time I have been asked how to open these two areas I would have a summer home. Shoulders and hips are the most mobile joints in the body and, therefore, are easily injured if not properly balanced with both strength and flexibility.
You will need a strap to follow this segment. You can actually use anything else that will hold the tension on the line, like a towel or rope. The idea of using a strap is to create heat and allow for isometric stretching during a yoga flow. Isometric strength and stretch work is great because it keeps the joint at one angle and the muscle contracted. This combo will really help with alignment.
These isometric stretches are great warm up before overhead squats and snatch work. The most important part is to challenge yourself to pull both ends of the strap so that the muscles get the full opening effect while staying in a contracted state.