Do not use yellow or orange on shoulder and knee armor,
for rattle can use Bauhaus gold and misted with brown, the brown
has to be closer to rust brown than chocolate brown. the secondary color
around the silver, hand paint it using beige or crème color
Back in my day, they use to call it "School Bus Yellow" for the main color, then another pale color (between yellow and beige) for the marks around the scratches and dents. Then lightly mist it and/or airbrush some medium brown (with those dented/scratched areas masked), you will have that effect.