This is my take on the Eightscarred warband colour scheme featured in the Khorne Daemonkin codex from 7th Ed. 40k. The main colours are dark red, black, and brass with silver elements added to the metallic areas.

General Information:

My general method is to lay down all the base colours for the model, then do all the shading in the recesses before moving on to the highlights.

I don't own an airbrush so the recipe will mainly consist of Games Workshop spray cans and brush on paints.

Priming:

I find the metallic sprays from GW tend to be a little on the transparent side, so an initial undercoat of grey helps.

Because with scheme has silver trim on the backpack, I primed it separately from the main model using a paperclip glued to where the pack attaches to the model.

1. Prime the model lightly with Mechanicus Standard Grey
2. Prime the backpack with Leadbelcher
3. Prime the main body with Retributor Armour

Brass (Armour Trim - Except for the Backpack):

1. Drybrush over the model with Balthasar Gold focusing on the pieces of trim
2. Shade the recesses and around any rivets with Agrax Earthshade
3. Highlight the fine points and sharp edges with Stormhost Silver

Black (Armour Ribbing and Panels - Shoulders, Backpack center panels):

1. Base with Abaddon Black
2. Highlight the edges with Eshin Grey
3. Highlight fine points with Dawnstone

Red (Armour Panels, Backpack vents):

1. Base with Khorne Red
2. Shade the recesses with Agrax Earthshade
3. Highlight fine points and sharp edges with Wazdakka Red

Silver (Details - Backpack trim, Weapons, Chain, Grenades):

For grenades, replace Nuln Oil with Athonian Camoshade

1. Base with Leadbelcher
2. Shade the recesses with Nuln Oil
3. Highlight fine points and sharp edges with Stormhost Silver
4. A rust effect can be added using thinned Skrag Brown in select recesses

Grey (Details - Cloth and Cables):

1. Base with Mechanicus Standard Grey
2. Shade the recesses with Nuln Oil
3. Highlight the edges with Dawnstone
4. Add a highlight to fine points and sharp edges with Administratum Grey

Blue (Details - Lenses and Power weapon rods):

1. Base with Sotek Green
2. Apply thinned Sotek Green just around the part to create a blue glow effect
3. Shade the recesses with Nuln Oil
4. Highlight the middle with Temple Guard Blue
5. Finer highlight of Baharroth Blue inside the Temple Guard Blue
6. Add a point highlight of Baharroth Blue mixed 1:1 with White Scar

Brown (Details - Leather pouches):

1. Base with Rhinox Hide
2. Shade the recesses with Agrax Earthshade
3. Roughly highlight the edges with Skrag Brown
4. Add a finer highlight of Ushabti Bone

Bone (Details - Teeth):

The main colour for the bone areas will be Ushabti Bone, but an undercoat of Zandri Dust will help it go on smoother since Ushabti Bone is a more translucent layer paint.

1. Base with Zandri Dust
2. Shade the recesses with Agrax Earthshade
3. Layer over with Ushabti Bone , leaving the darkest recesses still showing
4. Highlight fine points with Screaming Skull