If you have a well-used guitar, tiny scratches and nicks on the body are a fact of life. These minor blemishes do not affect the guitar's sound, and many feel they add character to the instrument. However, if you prefer an unblemished guitar finish, there are ways to smooth out the surface on your own. This is a minor maintenance operation; for any serious repairs, such as cracks or major surface damage, it is best to consult a professional luthier.
Buff the scratches or nicks gently with the liquid scratch-remover, applied with the soft cloth. For minor surface blemishes, this may be all you need to do.
Use clear nail polish or wood filler, depending on the guitar's surface colour, on any pitted areas or light surface cracks that are too deep to be removed by the buffing procedure. Apply the polish or filler carefully in the scratched areas only. Allow it to dry completely.
Use fine sandpaper to gently sand the dried polish or wood filler until the surface is smooth and even with the rest of the guitar's surface.
Apply matching guitar lacquer to the repaired area. Allow it to dry completely.
Seal the lacquered area with a sealer especially designed for finishing guitars. Once the sealer is completely dried, buff the area with a soft cotton cloth until it shines like the rest of your guitar.
For very fine surface cracks, non-gel toothpaste or even leftover (and cooled) cigarette ashes may work as an abrasive.
Do not attempt major repairs or refinishing on your own. This can permanently impair the guitar's sound. For major cracks or finish issues, consult a professional luthier.