Mostly a remix of Mediocre Hobbies approach
Apply a heavy zenithal drybrush of Ice Yellow over the entire miniature, focusing on areas where the light would hit and leaving the red brown in the shadows. Pay extra attention to face as we want this to be bright and the focal point.
Apply Plaguebearer Flesh all over the exposed skin areas of the model.
Apply several layers of Carroburg Crimson thinned 1:2 with water to areas where blood would be close to the surface of the Orks's skin. ie nose, lips, mouth, hands and elbows. Allow drying between layers to slowly build up red pigment. Avoid the teeth. Apply neat Carroburg Crimson to scars or wounds on the mini.
Paint metallic areas with Rhinox Hide , using two coats for solid coverage.
Carefully stipple Ryza Rust to the metal areas, taking care to avoid areas of Ork skin.
Carefully stipple a smaller amount of Fire Dragon Bright to the metal areas, again avoiding Ork skin.
Carefully drybrush metals with Gun Metal , focusing on sharp edges and leaving rust to show through.
Paint trousers with Basilicanum Grey , letting it pool in recesses.
Paint wraps, fabric, straps and boots with Black Templar
Paint red fabric with Blood Angels Red
Stipple Mephiston Red onto the areas of metal, aiming to place it in the middle of the armour plate, gun casing or helmet.
Stipple a small amount of Evil Sunz Scarlet into the Mephiston Red, targetting the middle of the section painted red. This provides a highlight to the red panel.
Gently edge drybush Gun Metal along the sharp edges of the metal elements to chip away the red. You can also sparingly stipple the flatter, middle section of the red metal to create chipping and visual interest.