Prepare The Surface:
Clean the scratched area with soap and water, and dry it completely with a clean, dry cloth.
Sand And Reduce The Scratch:
Spray water on the repair area and over a very fine abrasive sand paper (3000 grit). Gently sand the area of the scratch by hand with light–to–medium pressure. While sanding, a light foam will appear, indicating the abrasive is reducing the scratch. Wipe the sanded area to be sure the scratch has been removed. The area being sanded will look dull, but don't worry because the gloss will be restored in the next steps.
Compound And Refine The Scratch:
Use a quarter–sized amount of a rubbing compound onto a compound pad and continue to buff until the clear coat's shine is partially restored. Remove any remaining rubbing compound from the area with a clean, dry cloth before moving on to the next step.
Polish And Restore Shine:
Onto a polishing pad, place a quarter–sized amount of scratch remover. Polish the area until the shine is fully restored.
For added protection, apply automotive wax to the area, or even the entire vehicle.
To make things easy, there are kits like 3M's Scratch Removal System from automotive specialty stores. These types of kits have all the pads, product, and abrasives you'll need and are used in conjunction with a household drill, making the buffing and polishing stages even more effective than when it's done by hand. More information is available at www.3MCarCare.com.