i agree, those two are good tips, but for the Gold it's mostly about easy coverage...
most metals show stronger over a dark base, but Gold has a harder time covering straight Black than Silver does...
Brown, as a first coat over a Black primer, requires less layers for solid coverage...
i actually use Brown as a first layer for my Yellows, and sometimes my Reds as well...
for some reason, every Dark Brown i've ever used seems to cover Black so easily...
it saves a lot of hassle for getting those light tones over Black...
my tip is not to poopoo drybrushing...
as painters start out, they use it heavily, and turn out rough, chalky paintjobs...
then they move away from drybrushing to achieve smooth results...
selective drybrushing, for the right subjects such as fur and stone, is a great tool...
alternating washes and drydrushing on bases with any kind of texture is quick, and looks great...
same goes for fur...
the trick is just to incorporate each layer with a wash, even playing with different tones like Purple and Green when drybrushing with Browns or Greys...
just play around, like Bob Ross, and paint happy skulls

...
cheers
jah