I've gone for a black undercoat initially. I know that this makes the colours less bright, but I find it easier to paint onto - if I miss a bit, the black takes care of it. We'll see how we go.
For the insurgent infantry, I'm going with multi-coloured shirts. The Regulars with the Ztumre National Workers Intervention will have a more conventional uniform colour.
More to come....
Oh! and this would have to have been the first time I have ever painted 9 figures in half an hour!