Since I was unable to complete the weathering session at the recent Wamp event I was asked if I could translate my plans into a tutorial. Happily I excepted the offer and here it is.
From a weathering perspective I like to build things up step by step in the same way as they would happen in real life. For example, the first step would be for any paint on top of the base coat to chip off leaving the under lying colour showing through. Then in the weathering process undercoat would show up, followed by dark rust spots, grim, rust streaks, oil streaks, dirt and finally worn but shiney metal. In following the natural process the weathering looks pretty convincing and quite realistic.