Electrical ground question

[JL_]

Hi everyone,

my truck 1965 GMC.
I'll start with what works then my question.
Rear tail lights: running, turn signals and brake lights. heater fan
Not working headlights, Front running lights, front turn signals and windshield wipers. I have power to and from the fuses, haven't checked the switch yet.

I an thinking keep it simple... so my question. Is there a common ground for the front end? where is it?

next any thoughts about where to start tracing the wires?
am i correct chase power to and from switch then to the lights.thanks for your time
j