When I had my wisdom teeth out, my oral surgeon put in my post-op instructions for me to keep ice on my jaws, but also to keep my head and shoulders elevated with pillows while I slept, to help the drainage and reduce swelling. It worked really well.
A bag of frozen peas, corn or mixed veggies will also work as a good ice pack, since the bags will mold nicely around your face. Another option is to go to the first aid section of any drugstore and pick up some Blue Ice, which goes in the freezer, but is very flexible and reusable.
*Always* remember to put a towel or washcloth between your skin and the ice pack so you don't freeze your skin inadvertently.