As we have mentioned earlier in many other posts,when starting from a chord progression so as to improvise melodically, one good starting point is to create at first a simple melody as simple as the chord progression e.g. one note per chord which we have called simplicial submelody (like a one note per chord bass line).
E.G. Let us start with achord progression inspired from the laton jazz melody blue bossa in G major
Em Am
D7 G
C Am
B7 Em
Then we add one note per chord (mainly the middle 3rd whcich discriminates majors from minor) and so we get the (we simboloze the notes of the G major by the numbers 1,2,3,4,5,6,7)
1 4
Em Am
7 3
D7 G
6 2
C Am
5# 6
B7 Em
Till now we have not bridged the gap between the complexity of an improvisational melody and a chord progression (or complexity of the simplicial submelody).
But since for a chord of 3 notes we also have 3 possible notes for the simplicial submelody corresponding to being the 1st 2nd or 3rd, or 1st voice 2nd voice and 3rd voice, we may as well create many more simplicial sub-melodies that are x1% 1st voice x2% 2nd voice and x3% 3rd voice (x1%+x2%+x3%=100%) to the original simplicial submelody .
Now we do have the bridge between the complexity of one chord progression and the complexity of the improvisation melody. For each variation of the simplicial submelody (we may create easily a bundle and a dozen of then for each triad x1%+x2%+x3%=100% ) we ceate an alternative improvisation melody which is simply an embelishment of the corresponding simplicial submelody with waving of 2nds (or 3rds or 4ths and 5ths) and embelishment which is usually adding notes between two notes of the simplicial submelody as "bridge" or "bass-line" connectingthe two succesive underlying chords of the chord progression.
More advanced considereations include perceiving small melodic themes for any pair of succesive chords, and then variations of them by translations, inversions and dilations.
