[Painting]Thinning paints for airbrush?

My Vallejo paints just came in, including Russian Green.

I have set of GHQ T34s I would like to spray. I'm using the testors POS
plastic clip onto the can airbrush, hey, it works.

What I don't know is how much you need to thin the Vallejo paints. I've been
using Testors stuff straight. Anyone have any advice? I'd go the experimental
route but at 15ml to the bottle I would prefer not to waste much.