painting velvet (already doing costume scheming)

[hydrolagus.livejournal.com]

I liked my costume this year even though I didn't get to wear it anywhere, and I want to further improve it. What I have in mind involves a design on velvet with some black and some colors. The bug is that my fabric-painting knowledge does not include velvet, so a question for the more knowledgeable: would I be better off starting with black and discharging the areas I want to paint other colors, or start with white and paint each field? I'll be using thickened silk dye for my "paint."