Don't fully get the new shading method

Hey Kinean

Since your d.va tutorial im having a hard time wrapping my head around the method of shading that's becoming basically the new thing through out your videos. I mainly use the greyscale method you used prior to that change and after realizing it, am trying to adopt it into my own art style. How ever i have 1 or two questions regarding it since i dont get it 100%

1: How do you go about picking the "shading colors" (EG: The dark blue/pink on D.Va's suit, etc)

2: Figuring out the "lighting" colors.

Im just really boggled about it all since im trying to do it on a practice piece in preperation for my comic but im still not getting it in its entirely.

Thanks! Dingo.