I have attempted to train quite a few rookies in safe traffic direction. There are many dangers in playing toreador to hundreds of two ton cars. I have a few tips.
First and foremost: Wear your reflective vest! Regardless if it is night or day. The darn thing is ANSI compliant for visibility and you are not.
Second, know clear hand signals. Hard to recreate here, but hand signals in daylight are much different than using that flashlight and cone in the darkness. Simple movements to direct the cars are best. Waving them forward, pointing toward turns, and holding out a hand or light for stop work best.
Next, you need your whistle. One long blow for stop. Two short chirps for go. This auditory addition to good hand signals is essential if you want to get their attention. And you do.