The key to most of the advanced techniques like light sourcing, non metal metal, filigree and whatnot is just to find that point where your paint is as thin as it can possibly before the liquid separates from the pigment.
As far as glowing effects my best results come from painting backwards. Or, if you like additively. Starting with white primer wash on a thin yellow-white followed by a yellow followed by a yellow orange and so forth until its however dark you need it to be. The more layers you incorporate the better final result tends to be.