My friend's mum was told by her doctor to try this technique:
Sit upright and face forwards with your shoulders square.
Slowly tip your head towards your left shoulder as far as is comfortable, still facing forwards, and hold it for five seconds and then slowly return your head to upright again and hold for five seconds. Do this five times.
Then, tip your head towards the right shoulder in a similar manner, five times.
Then tip your head forwards five times, and then backwards five times.
This is good for helping to get rid of a migraine, but is also good for helping to prevent them, apparently. My friend's mum was told to do this technique at least once every day.