Edge highlighting
Running a thin line of lighter paint along the raised edges of armour and cloth so the shapes read at arm's length.
also known as: kanthighlight
The edge is not decoration; it is what tells the eye where one plate stops and the next begins. The common failure is running the line all the way around every edge, which lights the model from everywhere at once and flattens it. Pick where the light is coming from, highlight only the edges facing it, and leave the rest dark — a half-highlighted model reads as lit, a fully highlighted one reads as outlined.
First showcase: two Stormcasts in progress
Two Stormcast Eternals photographed mid-process, with notes on where the edge highlights went wrong and what I'll do differently next time.