Here is a Centauri Octurion Battleship I'm working on. I primed it a very light grey (white would have worked just as well) and then painted the whole thing with a mixture of Gold and Black (with a very very small amount of white). This gives me a very dark gold which will have a lot more depth in the finished miniature. It also makes the miniature not look so new.

The next step which you see here is where I take a brush that is wet with thinner and strip off the gold in the areas that are going to later be painted some purplish color which has yet to be mixed. This is done for two reasons, first that it is one less layer of paint over those areas so detail will be sharper and second, the color going there is going to be fairly light and it's easier to cover the light colored primer than the darker gold. Remember that the color you're painting on top of alters the color you're painting. This is where the primer being acrylic comes in handy because the thinner dissolves the gold but leaves the water-based primer untouched.

I'm kinda liking the white and gold look so far though...