A common thing I’ve heard for mandolin is to use the “one finger two frets” rule, where each finger is responsible for two frets. If each finger is responsible for 2 frets, then any 2 fingers have 4 possible positions. It looks something like this: The first combo (adjacent frets) is a ˝ step or Minor 2nd. The second and fourth combos are a whole step or Major 2nd The ...