Here is how I painted my very first Cadian. He was done as part of a general edge highlighting video, which can be found on my YouTube channel.
Regimental Khaki
Basecoat with Zandri Dust .
Wash with Agrax Earthshade and Lahmian Medium mixed 1:1. The thinning it go get the wash into recesses while minimising staining.
Add chunky highlights of Zandri Dust and Karak Stone mixed 1:1.
Do a fine edge highlight of everything with a mix of Karak Stone and Screaming Skull .
Selectively highlight everything with Screaming Skull .
Add selective specular highlights of Wraithbone to points and places where highlights meet.
Green Armour
Basecoat with Castellan Green .
Mix equal amounts of Castellan Green and Rhinox Hide and thin with water to a wash consistency. Now take a thin brush and recess shade the armour.
Now mix some Abaddon Black and add it into the Castellan Green and Rhinox Hide from the previous step. Now do a second, more selective recess shade. Making your lines as thin as possible.
Now make a 1:1 mix of Castellan Green and Straken Green . Use this mix to add a chunky edge highlight to the armour.
Now add a fine edge highlight with pure Straken Green .
Selectively edge highlight corners and exposed edges with Nurgling Green .
Now mix your Nurgling Green with an equal amount of Wraithbone and add specular highlights to corners, plus the centre of the previous stages highlights.
Black Leather
Basecoat with Abaddon Black .
Add a chunky edge highlight of Eshin Grey .
Add a fine edge highlight of Dawnstone .
Selectively highlight corners etc. with Administratum Grey .
Pop specular highlight of Administratum Grey mixed with a little pure white to corners.
Caucasian Skin
Basecoat with pure Cadian Fleshtone .
Now, just slap some Reikland Fleshshade over the skin.
Darken your Doombull Brown with some Abaddon Black and darken the area just around the eyeball on the face, framing the eye.
Shade under the eye gently with a 1:1 mix of Cadian Fleshtone and Thunderhawk Blue .
Reestablish the basecoat Cadian Fleshtone on raised/exposed areas, in preparation for highlights.
Gradually add Wraithbone to the mix, highlighting smaller and smaller areas. You should eventually be adding highlights of pure Wraithbone .
Bonus: If you want to add stubble. A glaze of Dawnstone works very well.