Summarize this article in one sentence.
Stay off your leg and do as little walking as possible.  Keep the knee elevated above your heart while lying down. Prop the knee and foot on pillows or on the arm of the couch. Use crutches if it hurts to straighten the leg or to put weight on it. If you need crutches for more than a few days, you should see a medical professional because it may be something serious enough to require more than home care. Apply ice directly on the swollen part of your knee for 10-20 minutes. Do this 3 times a day to reduce the swelling. You can also use a frozen cold pack or a bag of frozen vegetables like peas instead of ice. If you have sustained an injury that results in a swollen knee, avoid placing heat on your knee. This includes hot packs, hot showers, or hot tubs. Wrap your knee in an elastic bandage to apply compression. This will help decrease the swelling. Try an elastic bandage with a fastener that sticks to the bandage so that you don't need clips.  You can purchase a compression bandage at a local pharmacy. Be careful not to wrap your knee too tightly. If you notice any numbness, tingling, odd coloring, or increased pain, your bandage is wrapped too tightly. Massage at a very gentle rate may help increase blood flow to your knee. If anything hurts, refrain from massaging the painful area. Try an anti-inflammatory drug such as aspirin, acetaminophen, naproxen or ibuprofen - all are non-steroidal anti-inflammatory drug (NSAID).   When taking this type of pain reliever, be sure to carefully follow dosing instructions on the label. You can also try a topical painkiller. Talk with your pharmacist for proper application. You can also try a patch that contains the analgesic lidocaine for pain relief.

Summary:
Rest your knee. Ice your knee. Avoid heat for the first 48 hours. Use a compression bandage. Gently massage your knee. Alleviate pain with an over-the-counter pain reliever.