Firstly apply a cold compress, containing ice if possible, for 15 to 30 minutes. A bag of frozen peas is ideal for this. This will reduce blood flow to the sprained area and, therefore, minimise bruising and subsequent swelling. Apply, firmly, a crepe bandage and give the sprain plenty of rest until the discomfort has subsided. If possible, keep the sprained joint raised.
This will make it more comfortable and less swollen.