interestingly enough, i've never given that much thought to the proscess,... the answers here fascinate me,.... i dont publish that sort of thing here but when i get a song done it usualy began as a fast thought in my head, first a word or phrase that hit me, and then an entire verse will come together and a chorus,.... this usualy happens on the road at 75 miles an hour when i cant write it down without pulling over,... so i wind up singing it to myself until i reach a stopping point where i can whop out a pen and paper to write down the lyrics,.... the first whole half of a song will come together this way for me,.... the musical part, chords melody etc, i dont have to write that part, i can remember that till later,...
later, when i get myself back home and to the guitar, i will note the chord progression, the melody line is left to memory, and then i'll work out a second half to the song.
rarely, i will get the entire song in one gulp, it usualy comes in two halves, the first being spontaneous, the second being contrived, and then the third stage is edit to bring it together.
there may be an hour or so between these stages,... i've had gaps of months between the 3 stages.
thanks for giving me a chance to think the proscess through,... i've never done that before.