Knowing how to remove scratches from your car will keep it looking good, and perhaps more importantly help keep rust from attacking the bodywork. A car's paint job normally consists of multiple coats of three different types of paint. The first type is a primer, applied directly to the metal or other surface to protect the bodywork and promote the adhesion of the other layers. The next type is the color layer which is applied on top of the primer. The last type is the clear coat, the top layer which protects and seals the color layer.
The first step in car scratch removal is to determine if you actually have a scratch. If you run your hand over the area you may find that what you thought was a scratch is actually something sitting on top of the paint. You should be able to use a rag and some bug and tar remover to remove the blemish.
If the scratch isn't very deep the scratch removal should be fairly simple. First clean the surface well as any contaminants could add more scratches during the process. Apply some rubbing compound to a rag and rub it into the scratch. When the scratch has mostly disappeared switch to a polishing compound and polish the scratch and surrounding area. Follow this with a wax for further protection.
If the scratch is a bit deeper you can try wet sanding the area with 2000 grit wet sand paper. Ensure that the surface stays wet and that the paper stays clean (paint buildup on the sand paper can cause deep scratches in the paint). Be careful not to over sand as if you aren't careful you can sand all the way through the color layer. Follow this with 2500 grit and then 3000 grit wet sanding, rubbing compound, polishing, and finally wax.
If the scratch is deep (if you can feel it when you pass your hand over it or if you can see primer or bare metal) the job will be more difficult and you will need to use some sort of paint, such as a scratch repair pen. Make sure that the surface has been cleaned well. If the scratch goes down to bare metal start with a layer or two of primer. Next use paint that matches the exterior color of your car to build the scratched area up until its level with the rest of the paint. Cover with a layer or two of clear coat. Once the paint has dried use rubbing compound to level the surface, and finish with polishing compound and wax.