First I start sculpt with a dynamesh Polysphere

Put some skin details with alpha brushes

Now paiting with Polypaint with zbrush, and testing some diferent types of light

In Maya, try to put some studio lights, and testing AistandardSurface from Arnold

With all textures in your places, I multply the Epdermal and Subdermal to make a more dark skin for Killmonger. Put a Specular map to make his skin more shinning.

Hair made with NHair, and put some details of his costume from the movie.

Specular render passes from arnold 

Last render with Arnold with all assets includes.

Pos-Production with Photoshop, put some blur and dusts to make the character in his place.