Feel free to copy cat, it is a simple yet I think effective method and got some good comments yesterday at the tourney. I think Warriors will be awesome in 6th with the advent of hull points and the changes to Rapid.
The gold was just thin layers of Burnished gold washed in the same method to produce a more natural tarnished gold . The good thing also is that I undercoat my Necrons Adeptus battle grey which produces a more natural shade to the undercoat. Black and White is harsh and bleeds through, but not Adeptus battle grey - so you can apply your coats more evenly and not get paranoid with covering - so like the gold if you look closely (model to eye) you can see faint grey undercoat beneath the gold, but because its grey and because its washed it is not noticeable and looks more like a shade.