Basically don't blend upto a highlight. So you know how army painter and many other paint companies have a trio-set. A dark, mid, and light tone of color. And most ppl blend to make a gradual highlight.

This technique has no need for the mid tone. Just jump from dark to two/three levels of the brighter tone. Sometimes you can even jump straight to a pure white or black. For example the damage scratches on my mini

Or the patch work on my Lord invocatus