I have a fado guitar (scale length 44 cm, thus a type of mandola-guitar) with 6 courses of strings. I eliminated the double strings to be single thus it has 6 strings tuned by overtones tuning to
G2-D3-G3-B3-D4-G4. (and in degrees of a diatonic scale 1-5-1-3-5-1).
Therefore it is an open tuning to G major scale. I have put white marks on the notes of the G-major default scale across the fingerboard and for every string.
Because the fretbaord is at most 44 cm the improvisation is easy, and because the fado guitar has very bif sound box the sound is both sweet and strong.
The chords of the scale appear as vertical simple patterns across the 6 strings. This is very convenient and simple as we have all the scale and chords of the scale across the fretboard in the right sequence of their roots in the scale. One octave is of course the full 12-frets of the fretboard.
When improvising with melodically (sequence of single notes) or harmonically (sequence of 3rds or 3-note chords) we follow the next geometrically and harmonically convenient patterns
1) We go up and down a single string with oscillations around notes for a purely melodic improvisation, which is dictated purely from our emotional center over the melody note by note. We utilize repetition of a pitch-order and rhythmic pattern that would bethe first melodic theme.
2) We do the same but with double consecutive strings which make a major or minor interval of 3rds , pressing the fingers always upon the white marks,
3) We do the same but with 3 consecutive strings which make a 3-notes major , minor or diminished chord , by pressing the fingers always upon the white marks that define also the shape of the chord on these 3 consecutive strings,
4) We play 3-notes chords triads, on 3 consecutive strings where the dominating relation among the consecutive chords is being relative chords (minor-major with 2 common notes. It is odd or even order of chords
5) We do the same but with harmonic relations of the chords
6) We bridge two consecutive chords with notes upon the white marks making leaks and leads
7) We pair 2 or 3 chords that are consecutive in the order of their roots in the scale (chromatic relation of the chords) and bridge them with the melodic leads that interlink them. There is at least one bridge for each of the 6 strings that link the 2 chords, as each chords spans with a simple a patterns among the 6 strings due to the tuning.
8) We interpolate very often the open strings root chord
9) When we move in a melody up and down we try moving horizontally (chromatic melodies ) and vertically (harmonic melodies) with a proportion 1/3=33%, 2/3=66% respectively
10) We use blue notes of the scale in the melodic improvisation , e.g. 7b, 5# , 2#, 5b , 1# etc.
11) We utilize the diminished 3-notes chord , among 3 consecutive strings (the pattern is visible at the 7 degree of the scale) and resolve to1 semitone or 1 tone up or down nearest scale chord.
12) We utilize drone melodies where one note that of the open string interpolated among any two notes of the rest of the melody, in any string with the same order and rhythm pattern and because of the tuning this a modulation of the melody on the 1,3,5 modes (Ionian, Phrygian, Myxolydian) of the diatonic scale.
13) We may at the same time as in 12) to play isocratically the root open chord or only the 6th 5th strings that are 5th 1-5 while practicing the 12)
14) We start at the triad of minor chords of the scale 2m, 3m , 6m and we gardually with bridging melodic themes we shift to the triad of majors 1M, 4M 5M.
15) We play a chord of the scale (usually the 1M, 4M 5M) which is across the 6 strings and simplest pattern, but only partially each time 3 consecutive strings and the 3 other higher or lower on the same chord but asit changes octave and timbre of the strings are heard as...different chords or at least radically different voicings of the chords.
16) We play the andaluzian cadenza (6m, 5M 4M 3M) with melodic themes bridging the chords, (6 strings 6 bridges) we reverse to andaluzian ascenza etc.
17) Similarly we improvise over the triad of main chords 1M 4M 5M ) as in the 12 bars blues with links (6 strings 6 links or bridges) for each chord transition.