Here is the method I went with to get my Biel-Tan Guardian Defenders painted up quickly, but to a decent standard. The white armour is something I stunmbled upon idependantly, but the credit for the helmet goes to
Wiltrichs Miniature Art and his wonderful YouTube video "HOBBY BASIX: How To Paint Biel-Tan Aeldari Green Armour".

White Armour

1. Prime the miniature with Corax White .
2. Ensure you have a solid basecoat by going over the armour with Corax White by hand.
3. Was all of the armour with Apothecary White thin with the same amount of Contrast Medium . Ensure it doesn't pool anywhere unsightly.
4. Get some Dark Reaper nice and thin on your wet palette and recess shade.
5. If there are any areas you want to define even more, add a little Abaddon Black to the mix and add a deeper, more selective shade.
6. Edge highlight the armour with Corax White and White Scar , mixed 1:1.
7. Selectively highlight points and curves with a pure white (like White Scar ).

Green Helmet

1. Basecoat with Warpstone Glow .
2. Recess shade with an equal mix of Warpstone Glow and Rhinox Hide .
3. Add some Abaddon Black to the mix and add a finer shade to the deepest part of the recesses.
4. For the first higlight, mix Warpstone Glow 1:1 with Moot Green and apply as either a chunky edge highlight or a glaze towards the edges.
5. Add a fine edge highlight of Moot Green to the edges.
6. Selectively highlight points and exposed cureves with small amounts of Moot Green and Screaming Skull mixed 1:1.
7. Add specular highlights of Screaming Skull .