nucking futs paints these really well, if i remember correctly he starts off wit a matalic gold paint over all of it
then get a sponge and sponge it with browns and blacks and then brown again untill satisfied with the result
then seal it, comes out looking really good and close to the pic.
1. Layers: Your palette is great, but remember, things age and tarnish randomly. Thus, layers. Take your palette and bounce back and forth with the colors in the various areas, to give it more dimension in the tarnished ares.
2. Fading out: IMHO, the colors change too abruptly from one to the next. If you are using acryllics, use damp sponges (Completely squeezed) and paper towels to remove paint along the edges, to better fade it in. Also, when using sponges, keep in mind that manufactured sponges are too perfect and if you are not careful, the pattern that the manufacturer creates can be seen. Thus, some people use sea sponges, which are more eratic by nature. I simply took a pair of scissors and went batshit on a Scotchbrite sponge (The ones with a green backing) and cut into it to eliminate the manufactured pattern.
3. As Hez shows in his painting videos, a great way to add depth with rattle cans, is before the metallic paint dries, take the green scouring side of a scotchbrite sponge and scuff the paint. Doing this at different times, with different levels of pressure, will produce varied results. You can easily get multiple shades, sheens, out of one color, using this method.
4. It's only paint and can always be painted over and, damn it, painting it is the fun part, anyway!
I start off with matalic gold paint for base color the I use a dark copper color then black and copper again and just go a few shades of light copper and brass then a black wash here are a some of my bios everything is sponge no airbrushing at all