Hi Floyd Jane,
Yes, many times I do hum a melody, mainly to tweak the line lengths, although when I start putting the music to them, depending on the melody they may still need some revisions. Also, I will probably do some rewriting to try to make them better. Doing FAWM we are sort of under a deadline, but it's nice to get the song idea in a form that I can work with more later. I can come up with melodies pretty easily but the problem is coming up with interesting melodies. I am not as strong in that department and really liked it when other guys on this site did some of them. It allows me to have considerations for songs that I would probably never have thought of.