This is my first post on this site.  Please excuse me for beating a dead horse, I know my question has been asked multiple times and I've searched and read multiple threads on this topic.  This is my second build, this time I have included a volume pot (I know some say it's better without one) and a piezo encased in a wood block.  Pretty standard stuff, I flip the amp on and it hums like a beast untill I touch the cable.  From researching here I understand that I need to ground something.  I am embarassed to admit how little I know about electric current and wiring but it's pretty minimal.  I have attached a pic of the setup and a pic of my planned ground runs.  I plan on running a wire from the housing of the volume pot to the big hook thingy (pretty sure that's the technical term) on the input jack and then another wire from that same hook to the underside of one of my metal soundhole screen.  I see a lot of people run it to the bridge and I assume most use some sort of metal bridge, my bridge is bone inlayed in a chunk of cedar thats why I chose the metal screen.  Does this sound/look right?  Any other suggestions reccomendations?  Thanks,