Thank you. All my paints are from citadel brand (sold at gaeworkshop) I don't use any other varnish or something like that For the gold parts I fisrt apply a "beige/light brown" base, then shadowing to darker tones of brown and black. Then only I apply the gold layer wich is not 100% opaque. Once it's dry I apply more gold only on the highlights. I also use white lines one edges to reinforce the contrast. That's the technique I use to have vibrant gold tones For steel parts from black base I only dry brush 3 differents tones of steel . Then to make the "used" look more present I use citadel inks (shade "Nuln oil") on the overall figure (except flesh parts where i use citadel glaze "bloodletter" ink).
I've tasted tones of different brands of mettalic paints with all the same result in the end.