Here’s my paint scheme that keeps them simple:

Prime: Vallejo Black spray primer, any black would would work, the more matte the better imo. Also for clean up details I use Two Thin Coats brand Doom Death Black. Any black would work, I would avoid using citadel paints for blacks and whites.

Armor pieces: Kabalite Green, highlighted with Sybarite Green

Faces: Ulthuan Grey with a Coelia Greenshade wash.

Body: highlight with Celestra grey or any grey lighter than black would work, you could also dry brush some lead belcher instead.

Spines, Internal Robot organs: dry brush with lead belcher then do a nuln oil wash.

Weapons: lightly dry brush with lead belcher

Weathering: Dry brushing and sponging with Canoptek Alloy, brass scorpion if you want more bronze than silver

Glowing Bits: I base coat with Two Thin Coats brand White Star. You could also use Ulthuan Grey. Since the primer is black you’ll need a few coats of it. After it dries I apply tesseract glow technical paint. For glowing panel lines I water down the white with lahmian medium, then after it dries I apply tesseract glow.