Actually, breezy has a very good point there (no pun intended!), about plecks. On the mandolin, the pleck makes a hell of a lot of difference, which is why I usually carry a selection ranging from hard to flexy, and have even used gem stone on occasion. I suppose it could be the same on the guitar, although the tremelo effect on the mandolin is more subject to the pleck (I don't do chords).