The metals are very simple:
Basecoat with gunmetal.
Stipple with red-brown (sienna) all over and a bit more sparingly with some sort of orange (I used Vallejo Model Color red leather).
Wash with agrax earthshade (brown ink type stuff).
Highlight with thin glazes of gunmetal and then a mix with some sort of silver (I like Vallejo Model Air Alumunium) if necessary (sword on the green warrior dude is most noticeable).
Highlight edges with a more silver mix.