I usually put a bit of nail polish remover on the disc and wipe it clean, then wipe on a layer of petroleum jelly onto the disc. It works pretty well depending on how big the scratches are. But don't get nail polish remover on the title side of the disc though as it can potentially remove the art off of it. And be careful with the nail polish remover though, as it may completely ruin the disc if you do it incorrectly; remove ALL of the nail polish remover or it will fog up your disc permanently.