It's funny, Peace, but the one song I've written that gets almost unanimous raves from everyone I sing it for is one that kind of sprang full blown from -- or into -- my head one day as I was doing housework and singing 'aimlessly' for my own amusement. At the other end of the spectrum, among the songs I've written that most audiences seem to like, are songs where I've spent the 120 hours or so that you described fiddling with either the tune or some parts of the lyrics.   For me, at least, there's not one consistent "how-to" pattern.

I think melodies often do pop into the heads of musically-inclined people who are receptive to them. Sometimes lyrics do too. Part of the art is knowing how to capture the critters before they get away from you.