Actually, I use a white undercoat a lot of the time, with a thin black-brown wash 'wiped-off'.
But Argonor is right that I used a matt black car spray undercoat for these figures, drybrushed with Vallejo 'Flat Earth' to bring out the detail for painting - I find it just too difficult on the old eyes to paint on a pure black undercoat!
The highlighting process is much the same as that used by most people I think - I just tend to use more extremes, as Niels says.
You should also remember though, that owing to the miracle of digital photography, the colour intensity and contrast always comes up as a lot brighter and deeper in enlarged, on-screen images, than on the actual mini 'in the flesh'.
Thanks for the positive comments