How do I change a Unit's Hair Color or Skin and etc?

[Mr Hawk]

Hello. I have question? How do I change a Unit's Hair Color like for example the Peasant from Brown to Orange or the Hero Paladin Unit's Hair Color and Skin Tune, The High Elf Priest from White to Brown with the Newest Blood Elf Skin tune or just Void Elf Blue skin tune and etc?
I had tried this method but it ended up messing up the Hair Model with the different hair color and same with the Skin Tune?
Any Pro Tips or anything else like that?