Of course!
But there is nothing really special in it, and I doubt you will learn anything from me
(I remember your post about the techniques you used for the brass material on your beautiful locomotive...)
As for the materials, for the exterior I mainly use the TrainBumpSpecEnvMask shader. I'm always working with simple base colours in the modelling and raw unwrapping phase. For the fine texturing basically I use quite a lot of different layers in Photoshop; each layer with only a few variation in colour, and I also use different photo textures or "structures" with different blending modes, but usually very low opacity - only a few percents.
On the other hand it seems useful to have loads of different Photoshop brushes (dirt, grime, splatter and all that stuff). It took me a lot of time to experiment which were looking rather good and to play around with the settings.
Generally I need more time to get the textures more or less good looking than for the modelling
I'd like to go more in (hopefully useful) details but writing it down in english is too demanding for me tonight - after a very long working day...
Maybe with more concentration tomorrow. Needless to say that sharing experience about using materials and textures is very much appreciated, I imagine not only by me