Take a clean, lint free soft cloth and slide it underneath the strings along the fingerboard. Gently rub the string back and forth with the cloth and rub the cloth against the finger markers on the finger board. Do this daily after you are done playing for the day.
Moisten a cotton ball with rubbing alcohol. Rub the cotton ball up and down the fingerboard, wiping the grease, smudges and rosin from the strings, finger board and finger markers. Your cotton ball will get quite dirty so throw it away after wiping down this area once and repeat with a fresh cotton ball. Do this once a week or once every two weeks.
Allow the fingerboard to air dry for around 15 minutes.