This is my take on the original paint scheme of the 14th Legion, which would eventually become the Death Guard.

The main colours are grey, red, and gold.

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 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.

1. Prime the model lightly with Mechanicus Standard Grey
2. Prime over that with Retributor Armour

Gold (Armour Trim):

I generally start with the armour trim so that any time I get paint on another piece its easy to cover later.

1. Drybrush over the model with Retributor Armour to even out the colour
2. Shade the recesses and around any rivets with Agrax Earthshade
3. Highlight sharp edges and fine points with Stormhost Silver

Red (Armour Panels - Right Arm):

1. Base with Khorne Red
2. Shade the recesses with Agrax Earthshade
3. Highlight the edges and around the inside of the armour trim with Wazdakka Red
4. Add fine points with Kislev Flesh

Grey (Armour Panels):

1. Base with Mechanicus Standard Grey
2. Shade the recesses with Nuln Oil
3. Highlight the edges and around the inside of the armour trim with Dawnstone
4. Add fine points with Administratum Grey

Black (Details - Armour Ribbing, Weapon Casing, Tubes):

1. Base with Abaddon Black
2. Highlight the edges and add scratches with with Eshin Grey
3. Add fine points of Dawnstone

Silver (Details - Chains, Weapon):

For grenades, replace Nuln Oil with Athonian Camoshade

1. Base with Leadbelcher
2. Shade the recesses with Nuln Oil
3. Highlight the edges with Stormhost Silver

Brown (Details - Leather Pouches, Belt, Wrap):

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

Blue (Details - Power Tubes):

1. Base with Sotek Green
2. Shade the recesses with Nuln Oil
3. Layer the middle with Temple Guard Blue
4. Add a fine highlight of Baharroth Blue

Beige (Details - Horns):

1. Base with Rakarth Flesh
2. Layer the upper half with Skrag Brown
3. Shade over with Agrax Earthshade
4. Highlight the lower portions with Rakarth Flesh
5. Tip with Abaddon Black