When I first put my spyder projectors in I didn't plan it out much just winged it. It worked but it was a mess of wires and if I needed to take the headlight out it was a pain to make sure things went where they needed to. I also needed to wire in a resistor for my led signals so I figured I'd wire them with a harness connector.
So what I ended up using for a harness since I was too cheap to buy one was a 4 wire connector for a heated O2 sensor off a grand prix (luckily pick n pull is full of them)
Soldered the connector to the headlight
Cleaned it up with some split loom.
Did the same to the harness on the truck. You can see the led resistor mounted to the rail at the back.
Plugged it in and checked and everything worked. Now there's a connector for the headlight bulbs, the signal and the halos and leds. No more fidgeting with 5 little wire connectors that look like a rats nest of wires.