Other techniques
The above technique works well. The ‘Eavy Metal team uses a very similar technique. If you’d like a more rich gold tone, try washing it with thinned-down Chestnut Ink. If you’d like a lighter tone, try mixing shining gold with Mithril Silver for successive highlight stages. For an antiqued look, undercoat with black, then paint the area to be painted gold Leprous Brown, and trace over this with shining gold, and wash with thinned-down Chestnut Ink.