It all depends how you want your minis to look.
My general theory on painting is never drybrush. It always looks a little naff. I'm not saying it can't work and it works fantastic for quick army painting but if you're aiming for great looking minis as opposed to rush job, then don't drybrush.
Also, if they're white armour I wouldn't undercoat black on 6mm minis - it can work but it generally needs a lot of coats of white. I'd start with a white u/c and wash with a grey then repaint the white leaving the crevices and depressions on the minis grey. With the reds and blues however I would start with a painted u/c of black. It will help deepen those colours against the starkness of the white. Red particularly will be really bright on a white u/c. This will mean you'll be doing a lot of black detailing at first but it will help define the other colours.
This is how I would paint them, but I'm sure others may have a better approach if you don't like the idea of so much detail.
Good luck! ÂÂ
