Relays is one of the first things you should consider, along with going through the headlight wiring from the switch, through the bulkhead and dimmer switch, and the sockets and grounds out front
Check battery charging voltage, as well as headlight voltage AT the headlights.
I'm running "cheap ol" Sylvania halogen sealed beams, because (LOL) I got 6 of em for free out of junkers. They work amazingly well WHEN you get proper operating voltage to em!!!!