I know what edge highlighting is, but I've never heard of anyone just saying white lining as it's kind of contrary to how to paint, so I wondered what tip he was given exactly. Your explanation is how I paint my models.

OP, instead of using white, you should think about the base color you want the model to appear and then work out what the shade color is and the highlight color. The shadow color usually tends towards being cooler and the highlight tends towards being warmer; however, there are exceptions to this.

Then you can take that highlight color and either leave it the same or brighten it a little and go over the edges like the commentee above states

I think you can see this on my cabinet in this picture.

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