i don't write many songs but when I do they usually arrive almost comlete with the tune and lyrics seeming to float in from some melody or theme i have just been messing with in quiet moments with a guitar in my hand - for instance having arrived early at my folk club last week with no-one about i sat down tuned up my guitar played a chord and the first line popped into my head within ten minutes the song was complete and i performed it later that night and subsequently with my band the following week to a great response.
When I have deliberately tried to write a song i have invariably failed even when a theme / story was presented to me - so maybe the earlier post about the muse fits the bill for me also. either way I just make the most of it where possible and resign myself to wait for the next visitation tight lines M