If I find something I like, I'll chase it and see what comes out the other side. Once a song gets momentum and gets away from you, that's a good sign. ↗
When I listen to my favorite songwriters, they have such simple melodies and chords. I occasionally manage to stop at the right time, but all too often I keep on going until I have way too many notes and words. But that's just what I do. ↗