You might just start with changing the coil wire to the distributor. The coil wire always breaks down first.

Check the resistance in the coil wire with an ohm meter. It should pass current with only a little resistance.

Also: Have the battery checked. It may be breaking down.

Also: Have the ground wire checked, and the grounding strap. Both can break down internally and look great but pass little or no current.

And clean your connections to the battery. I have seen a little bit of build up on a battery terminal shut down an entire electrical system.