I have just completed a chapter on minor scales. It covered relative minor scales, harmonic minor scales and melodic minor scales. I understand the basics in that I know how to count them out but what I would like to know is which scales should I try to learn first? My instrument is guitar. I have no idea when to use these various scales.

I assume that the melodic and harmonic scales are for improvisation and do not have a key signature like the relative minor. Am I correct?

Thanks so much for everyone's help.

Wishing you the best,