In Chinese Medicine we view migraines as a constriction whereby blood and body fluids do not flow up into and around the head as they should. In other terms, there is an imbalance of the Yin and Yang which can manifest as too much qi and blood in the head, or conversely, not enough. So we work to correct this imbalance depending on other symptoms you might present with.
In my experience, a lot of migraine sufferers also suffer from shoulder, upper back and neck stiffness or pain. This is a great place to start treating as it's not hard to imagine that constriction in this area will ultimately affect the easy flow of blood and body fluids into and out of the head area!