Spearmint works best. (I'm joking it doesn't matter)

Just copying from a thread

1. Smear toothpaste all over the disc. Make sure its an even spread, and that it's thick enough to stop the disc from shining through. 
   For a nice even spread, put a few blobs around the disc, and smear it with your finger. Circular motions help to cover the disc well.

2. Once the disc is nicely covered, leave it for a few minutes. Not too long, just 2-3 minutes.

3. Wash it off under cold water. Don't be force it off, just hold the disc under the water, and all the toothpaste should wash off. 
   If there are any particularly stubborn bits, rub it of very gently with your finger.

4. Dry your disc. Use the towel to very softly dry it. Don't be rough, or you'll scratch the disc again.