I have a similar background. I played piano for about 10 years and then haven't touched an instrument for about 8 years before picking up the mandolin last year. I'm still very much a mandolin beginner but I'm making progress.
Originally Posted by mel95
I'm taking the occasional lesson which I personally find useful.
I went through an exercise where I selected some relatively easy melody lines that I know well and slowly picked my way through the tunes. I left my electronic tuner attached to the headstock so that I could use that to identify where the notes are in first position on the fretboard. A couple of sessions like that and I quickly found my way around the fretboard from 0 to 6th fret on all strings.
The result is that I am now fairly confident playing my mandolin from standard notation. I don't play fast yet, but I can think of music the way I did on piano. That is, in terms of "B, then A, then C" rather than as fret positions "2, 0, then 3".
BTW, moving up one fret is moving up one semi-tone (or one key on a piano). So, on the...
G string: fret 0 = G, fret 1 = G♯, fret 2 = A, fret 3 = A♯, fret 4 = B, fret 5 = C, fret 6 = C♯
D string: fret 0 = D, fret 1 = D♯, fret 2 = E, fret 3 = F, fret 4 = F♯, fret 5 = G, fret 6 = G♯
A string: fret 0 = A, fret 1 = A♯, fret 2 = B, fret 3 = C, fret 4 = C♯, fret 5 = D, fret 6 = D♯
E string: fret 0 = E, fret 1 = F, fret 2 = F♯, fret 3 = G, fret 4 = G♯, fret 5 = A, fret 6 = A♯