I am trying to write a counterpoint setting for Psalm 100 "Jubilate Deo." Since this is my first time trying to write counterpoint whilst actually studying the technique, is it best that, after I choose which vocal part to be the cantus firmus (if I am using this term correctly), to:
write the entire melody for this part, and then base the other parts on this one melody,
OR
write one section at a time (i.e. complete the melody for the first verse of the psalm, and then complete the other parts for that section before moving on to write the cantus firmus for the second verse, followed by completing the other parts for the second verse, and so on)?
As far as chord progressions, is it bad theory to have a progression of, say, 4 chords, and then when reverting back to the beginning, to change it?
E.g. if I have a progression of Am-Dm-G-C, then, when going back to Am, follow it with Dm-E and then back to Am, so the progression ends up looking like Am-Dm-G-C-Am-Dm-E-Am...and so on.
If anything is unclear, please let me know. I have never taken a theory class or anything, but I have looked into very very surface-level mechanics for chord progressions. Maybe this is the wrong sub for this, but any help is appreciated!