I stole this, it's pretty good.
Grey Beard:
Basecoat Codex Grey
First highlight Fortress Grey
Final Highlight Skull White
Blonde:
Basecoat Snakebite Leather
First highlight Bubonic Brown
Final highlight 2 parts Bleached Bone 1 part Bubonic Brown
Ginger:
Basecoat Terracotta
First Highlight 50/50 Terracotta and Blazing Orange
Final Highlight Blazing Orange
Brown Beard:
Basecoat Scorched Brown
First highlight Vermin Brown
Final highlight 50/50 Vermin and Vomit Brown
Black:
Basecoat Chaos Black
First highlight drybrushed Scorched Brown
Finalhighlight 50/50 Chaos Black and Codex Grey
Grey Beard:
Basecoat Codex Grey
First highlight Fortress Grey
Final Highlight Skull White
Blonde:
Basecoat Snakebite Leather
First highlight Bubonic Brown
Final highlight 2 parts Bleached Bone 1 part Bubonic Brown
Ginger:
Basecoat Terracotta
First Highlight 50/50 Terracotta and Blazing Orange
Final Highlight Blazing Orange
Brown Beard:
Basecoat Scorched Brown
First highlight Vermin Brown
Final highlight 50/50 Vermin and Vomit Brown
Black:
Basecoat Chaos Black
First highlight drybrushed Scorched Brown
Finalhighlight 50/50 Chaos Black and Codex Grey