Subject matter is always the problem for me. Once I lock in on a subject the rest of the process is relatively simple. This is not to imply that the song is worth a hoot when it's done. Maybe one in a hundred are performable, but the junk seems to stack up and, eventually, something inspires an OK song. The biggest thing for me is to WORK at the craft. Consistency brings results for me. Finding subject matter is the key. My friend, Dennis Kingsbury, has written some great songs based on newspaper articles. I'm always impressed that he can find the song within.