Another approach which I use is to make a song by sound/chord experimentation/hacking around on keys or guitar. I come up with or make what is to me an interesting chord progression or musical piece and then the mood of the music helps me to inspire you with words appropriate to the music.

The two basic song writing methods are lyrics first then add music to match the lyrics the other is music first and add words to match the music. Both methods are valid and I am sure some songriters use both methods or even blend the methods.