Wear a knee brace to stabilize the knee and protect it from further injury.
Take anti-inflammatory painkillers. Non steroidal anti-inflammatory drugs (NSAIDs) like aspirin, ibuprofen, or naproxyn will help with pain and swelling. Follow the directions exactly. Talk with your doctor or pharmacist if you have any questions or feel that you still need them after 7 to 10 days.
Practice stretching and strengthening exercises if your doctor recommends them. Never stretch so much that it hurts. Ask your doctor to recommend a physical therapist for guidance.