When cleaning the surface of a DVD or CD you need to use a terry cloth. A terry cloth will not scratch the surface of the DVD, so it works perfectly. If you wear glasses you should have a terry cloth for cleaning them.
Step2
You need to buy cleaning solution. I use Opti-free cleaning solution. It can be found at office max for a few bucks. You should NEVER use toothpaste or water as these options don't work.
Step3
Add a few drops of your solution to the terry cloth and wipe away from the center of the DVD surface. Don't clean in a circular motion as this will not clean DVD properly. Always wipe out from the center(see the video).