To start with, buy Mel Bay's book on Mandolin cords. It's a great starting point for guitar players to visually see the differences and similarities in guitar/mandolin cord structure.Scales are important but cords get you going on the instrument much more quickly. You can't bend strings but "pull offs" can be quite effective. I found I can get a Martin Carthy -like melody on the mandolin where I found it near impossible to duplicate the style on the guitar. Good Luck.    David