undercarrage neon lights

im currently instaling some neon lights and it says to connect the red wire to a 12V powersource, what would be the best place or wires to connect it to, i was thinking to connect the lights as a 12V power source. or is there a better way

i would just run a wire to the battery and hook up a switch to turn it on and off inside the car. seems to me like the simplest method.