Thank you Jamo_S. That looks like what I need. When I studied piano in Philippines my instructor gave ma a piece of music. Memories in C with instructions to play second time thru in Db and third time thru in D. In two or three places in the piece he entered a C scale run and indicated that I should use this run to modulate to the next key. I left the Philippines before completing this lesson. Now I want to try it on baritone ukulele., It is suppose to make the song sound good. Memories is from the movie Cats but I play it slower and more dreamy, however I never learned to modulate. Thanks again my friend. Now time to practice.
In terms of able to play melodies in any key and intuitively, that means hearing something in your head and able to find and produce the same notes on keyboard, it is easiest to avoid the open strings.
Of course we should be able to use the lowest notes possible with our quite limited instrument range, because it is in the melody range. Re-entrant, but also with low G ones. Remember we as humans have also a limited singing range too, and sometimes need switch octave down or up. So it is too especially with re-entrant soprano with limited number of frets
Some think of "boxes" in the fretboard, but I rather think also of sliding up and down the fingerboard changing "positions". Or just play something with a one string, if that helps to get the idea.
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Another thing is that an uke or mandolin or an electric guitar higher up the neck, while all them are then in the melody range. They won't have exactly the purity in notes.
In C or any key the 5th (G) and 4rth (F) notes are fine, but other notes and also in relation to them, D, E, A and B, leaves much to be desired in terms of intonation, accidentals too if some different kind of scale, because of our equal temperament 12 tone fretting system.
That and also the usual intonation problems, because of the strings like mostly in C string if uncompensated saddle and anyways, bridge error etc. in general for all strings. We also have a tendency to bend them sharp in error.
Blues being simple and those 4rths and 5ths being in good intonation mostly and are most important, and the others can be achieved with bending what wanted to work beautifully in tune. Not that usually they even are, because depends a lot of the bender. Not with mandolin of course
Other music is always just so and so in terms of melody play. Compared to human voice or violin. No 12 equal toned tempered instrument is really fine for fine melodies. Be it keyboard or whatever.
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This is wonderful by this Brazilian duo:
https://www.youtube.com/watch?v=VXGjOrHvyNU
We can only play with our mediocre capabilities and love the music we produce, compared to them
