Slightly amended version of my Fire Warrior recipe. Works great on Battlesuits, drones and vehicles.

Undercoat with Mechanicus Standard Grey

Mechanicals

1. Base with Abaddon Black
2. Wash with Nuln Oil
3. Highlight edges with Mechanicus Standard Grey
4. Fine highlight with Administratum Grey

Armour Plates

1. Base with Dawnstone
2. Line panel edges, joins, and deep recesses carefully with Basilicanum Grey
3. Shade recessed areas with a mix of Mechanicus Standard Grey / Contrast Medium
4. Touch up panels with Dawnstone
5. Highlight with Administratum Grey
6. Fine highlight with Celestra Grey

Armour Plates (Dark Grey)

1. Base with Eshin Grey
2. Line panel edges and joins with Basilicanum Grey (if not already done)
3. Touch up panels with Eshin Grey
4. Highlight with Dawnstone
5. Fine highlight with Administratum Grey

Note: I didn't paint any armour panels with deeper recesses this colour, so didn't need a recess paint colour. That said, I considered using a mix of Eshin Grey / Corvus Black / Contrast Medium for any recesses on these plates.

Armour Plates (Yellow)

1. Base with many thin coats of Averland Sunset
2. Layer with Yriel Yellow (also many thin coats)
3. Shade recessed areas with a mix of Averland Sunset / Yriel Yellow / Contrast Medium
4. Shade deep recesses with thinned Dryad Bark / Contrast Medium
5. Line panel edges and joins with Agrax Earthshade
6. Touch up with Yriel Yellow
7. Highlight with a mix of Yriel Yellow / Screaming Skull
8. Fine highlight with Screaming Skull

Fire Caste logo (chest & shoulder)

1. Base with Corvus Black
2. Line the Fire Caste symbol with either Basilicanum Grey (for a black logo) or a mix of White Scar / Contrast Medium (for a white logo).
3. Touch up the outer with Corvus Black
4. Highlight with Mechanicus Standard Grey
5. Fine highlight with Administratum Grey

Gyrostabilizers (jetpack & elbows) & other metal

1. Touch up undercoat with Mechanicus Standard Grey
2. Base with Retributor Armour
3. Line recesses between the 'halves' with Agrax Earthshade
4. Clean up the two 'halves' of the gyrostabilizer with Retributor Armour
5. Layer with a mix of Retributor Armour / Liberator Gold
6. Highlight with Liberator Gold
7. Fine highlight with Runefang Steel

Red Lenses & Lights

1. Base with Khorne Red
2. Layer the majority (about 2/3 to 3/4) of the lens with Mephiston Red
3. Highlight with Wild Rider Red in the area furthest from the 'glare'
4. Fine highlight with Fire Dragon Bright
5. Paint a tiny dot of White Scar in the corner where the remaining Khorne Red is showing
6. Very lightly drybrush the area the light shines on with Mephiston Red to give an 'object source lighting' effect (optional)

Blue Lenses, Lights and Plasma Effects

1. Base with Stegadon Scale Green
2. For plasma, layer with Sotek Green . For lights and lenses, layer with Thousand Sons Blue
3. Highlight with Temple Guard Blue
4. Fine highlight with Baharroth Blue
5. For 'jewel'-type lenses and lights, paint a dot of White Scar in the corner
6. Highlight the edges around the vents of plasma weapons with a mix of Temple Guard Blue / Baharroth Blue
7. Very lightly drybrush the area the light shines on with a mix of Sotek Green / Temple Guard Blue to give an 'object source lighting' effect (optional)

Sept Markings

1. Carefully freehand on sept markings with Yriel Yellow (or Dawnstone if painting on yellow panels)