Painted in warmer colours than Night Goblins tend to be; and with non-metallic metals:
I haven’t mastered non-metallics yet; but it’s something I intend to focus on this year. In the past, when I’ve not been happy with the finished effect, I tended to re-paint them with regular metals. But although they’re not rendered flawlessly here, I think it’s better to live with the imperfections – and to keep working at improving the technique.
Worth a look
Genestealer warband (Leskouzes)
Tutorial on painting non-metallic swords (thefantasyhammer)
Tutorial on painting freehand designs (figurementors)
Crazy Ivan (forgemechanicus)
Kharn work in progress photos (flameon)