- Prime with a pure white - e.g.   White Scar  
- Fill in all weapons, armour joints and visors with   Black Templar  . Tidy up any edges/etc with a pure white like   Matt White  
- Wash armour with   Soulblight Grey  - while it's drying, wick away the majority from the flat armour panels. 
 
 Alternatively you can use a 2:1 mix of   Lahmian Medium  and   Soulblight Grey  , which knocks it back enough where you can get away with a standard wash.
- Using AK Weathering Pencils, mark the armour - I like to hit the edges of any equipment/weaponry with Dust/Rainmarks W26, then randomly hit the armour edges/panels with Earth Brown W28, Concrete Marks W27 and Streaking Dirt W30.