The pattern of a melodic minor key is: tone - semitone - tone - tone - tone ... major key signature and raise the seventh note of the scale. For example, in A harmonic minor there are no sharps ...

To do this, tune into open G by dropping the sixth, fifth and first strings down a tone, then drop the second string down a semitone to a Bb – that’s the all-important minor 3rd in the key of G.