Gold paint is made by mixing yellow colored paint and brown colored paint together in equal proportions. The more yellow paint that is used, the brighter the gold color.
It is possible to get different shades of gold by mixing different colors in with the yellow and brown paint. Mixing orange into it gives the gold paint a duller hue, while using white paint to balance things out brightens up the final result. Using a sparkled paint or even just adding sparkles to the batch while mixing creates a shiny and flecked gold paint that very accurately mimics a real gold item.