Singing

Throughout history, music students have learned to sing melodies before learning how to play them on an instrument. This has proven to be one of the most effective methods of understanding, appreciating, and memorizing a piece of music.

Of course it is not always easy to sing honkyoku, and maybe humming is a better approach. In any case, a worthwhile goal is to be able to look at a piece of honkyoku notation and vocalize the melody in some manner. The quality of your voice doesn't matter -- you're the only person who has to listen to yourself.

I firmly believe that the more you vocalize melodies, the stronger you will become as an all-round musician, no matter what instrument you play.