A very good habit to get into, is making sure you wash your hands before you play. Especially if your instrument has a fretboard made of Palisander wood or very similar woods. A lot of instruments do feature these fretboards. But, let’s be honest here, very few people will think of doing that every single time.
If your fretboard gets truly dirty through use it is generally recommended you do a thorough cleaning and maintenance job, once or twice a year. In this case you can use steel wool of the finest grade (000 or 0000) and then apply lemon oil with the help of a soft cloth.
Since an image is worth a thousand words, we have made a small video for you that should explain all. 🙂