I usually can't write the lyrics first. I might have an idea, but generally the lyrics and chords come together. I literally play with a sheet of paper, and keep stopping/starting to write, cross out, revise, etc. Once I get the basic structure, I can often write the second, third verses, but I have to develop them together. The music sets the mood (but I'm not a very good musician, so this is probably because I can't write appropriate music unless I have it at creation time).
I also write fiction! I love it. I'm always fine as long as I have my last line. To me, that's the anchor.