Hopefully, this little article will help you with some weathering techniques for both metal and nmm painting styles.
For this article I will be mainly using citadel colour, with the exeption of vallejo smoke.
I know this isnt an article about nmm, so it may not help with the theory of nmm, but it is mainly for nmm colour reference.


nmm weathering

I primed this mini in black, and covered any missed areas with watered down black paint:


I then made a mix of scorched brown,enchanted blue, snot green and water:
(6:2:2:1, respectively)

and painted this thinly onto the metalic areas.

I then mixed in a little bestial brown into this mix and put this on the areas that most of the light would hit the model.

This is what it looks like on the pallette:

I mixed a wash of enchanted blue, snot green and a spot of skull white with water.
(5:5:1:9)

I washed this all over the metal areas. do not worry if it looks messy, as it will look good when it is dry.

This is what it looks like once it is completely dry.
Dont try to blow dry it, as the wash will run out of place.


 I re-painted most of the metallic areas with the scorched-bestial mix, leaving the 'green' wash in the recesses.