Well, belive it or not, if you buy a roll of auto wire from wall mart, and look on the back of the package, you'll see what gauge to use for most interior electrical such as cigarette lighter is 14 gauge, for headlights and other under hood electrical, I'd use 12. I'd use ither 12 for the ign. most of the wiring should have only a positive side. Gonna need a fuse block also, any fuse block will do as long as it's not from a comp controlled car.