This is my take on the colour scheme of the Invocators warband, based on the art in the 6th ed. Chaos Space Marine codex.

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 black helps.

1. Prime the model lightly with Chaos Black
2. Prime over that with Leadbelcher

Silver (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 Leadbelcher to even out the coverage.
2. Shade the recesses and around any rivets with Nuln Oil
3. Highlight raised edges with Ironbreaker
4. Highlight fine points and sharp edges with Stormhost Silver
5. Add rust streaks with thinned Skrag Brown

Red (Armour Panels - Upper Third):

1. Base with Khorne Red
2. Shade the recesses with Black Templar
3. Highlight the edges on upper facing surfaces with Wazdakka Red
4. Add a fine highlight of Wild Rider Red

Blue (Armour Panels - Middle):

1. Base with Kantor Blue
2. Shade the recesses with Black Templar
3. Highlight the edges on upper facing surfaces with Caledor Sky
4. Add a fine highlight of Teclis Blue

Purple (Armour Panels - Lower Third):

1. Base with Naggaroth Night
2. Shade the recesses with Black Templar
3. Highlight the edges on upper facing surfaces with Xereus Purple
4. Add a fine highlight of Genestealer Purple

Black (Details - Cables, Tubes):

1. Base with Abaddon Black
2. Highlight raised edges with Eshin Grey
3. Add a fine highlight with Dawnstone

Gold (Details):

1. Base with Retributor Armour
2. Shade the recesses with Agrax Earthshade
3. Highlight the edges with Stormhost Silver

Brown (Details - Leather Pouches, Belts):

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

Blue-Green (Details - Lenses, Power Cables):

1. Base with Sotek Green
2. Shade the recesses with Drakenhof Nightshade
3. Highlight the middle with Temple Guard Blue
4. Add a fine highlight of Baharroth Blue

Tan (Details - Parchment):

1. Base with Rakarth Flesh
2. Shade the recesses with Rhinox Hide
3. Add a fine highlight of Pallid Wych Flesh