One of my three current projects - the Scavenge Skirmish Survive project is getting a bit more love these days as a Lead Adventure painting league in the Post Apocalyptic section is running.
I try to make the colours muted and the and avoid sharp highlights. Obviously there is a lot of washing and drybrushing going on too. I find these techniques are unbeatable for quick and easy dirtying/worn look.
The project goes on laboriously... If you need reminding the other two projects are 6 mm VSF in the Sudan and 28 mm Orks.