For a dunkelgelb base, I use MM Rust enamel slightly thinned and applied with a toothpick to simulate scratches and get into crevices. I also will follow along behind that with artist pastel burnt umber to accentuate edges/panel lines, etc. and when dull coated, that pastel sinks right in just like a wash but more precise IMHO.
Lots of different ways to produce this depending on your paint of choice, your method of sealing (or lack thereof), and if you want to use wet or dry methods.