WIRING NIGHTMARE
I'd try to mirror the OEM wire colors so you are consistent with OEM wiring schematics.
You are going to rack up a fairly substantial wire bill buying all the colors and length you need. Keep that in mind and compare with buying an already built harness.
Some colors may be difficult to find and trace colors are tough. There are specialty wire houses that will put trace colors on, but, usually have a large minimum qty.
Don't be afraid to upsize wires that carry significant loads or put relays in a stealthy location like I do with my headlight relay kits.
Mattax has some great suggestions and I will say stay FAR away from any wire manufactured in china... Seen wire that was 12ga OD and 16 ga wire inside, shady stuff. Stick with US made wire if you can even though it may cost a bit more.