A few years back someone on ASAP posted a good group of paints to use. I've used this recipe myself to make some nice looking paint jobs on Zats etc.
The paint is called Sophisticated Finishes and is made by Triangle Crafts. I've seen it for sale at craft stores like Michael's and Pat Catan's. You want to get the Blackened Brone and Gold colors for your main coat. I don't remember if the correct way to do it was to mix the two, or to apply one as a base coat and then the other for highlights. I think I did the later, but just don't remember for sure.
Anyway, the third paint you want to buy is from the same line. It's called Patina Green. This one is used to age the prop, and generally goes around the Jaffa lines. This particular patina actually oxidizes the metal, and produces a very nice effect! Just don't do what I did, and spray the patina through an airbrush or the metal parts will get oxidized too
