The more contractions, the better. Moving your ankle around in a circle is also useful. Running in a pool is a very effective way to build up your ankle support. Hopping up and down off a small curb can also be helpful. There are a variety of ankle supports that can help prevent re-injury.
Many athletes change to high-top leather sneakers for some additional support.
For athletes where repeated injury occurs despite exercises and braces, surgery to repair the ligaments torn is to be considered. Most achilles tears occur in individuals 30-40's who do not sufficiently stretch prior to athletic participation. They start playing hard, feel that they been shot in their calf, and have ruptured their achilles. This injury can be largely prevented by spending a few minutes before a sporting activity and stretching the achilles tendon. This can be done by positioning your body against a wall with your foot located behind your body.