A quick writeup of how I approach NMM for Imperial Black Armor (worn by Moff Gideon, Death Troopers, etc.).

1. Prime model Black and work from dark to light.
2. Armor plates start from Dark Grey and mix in Russ Grey (alternatively work up to Wolf Grey for more of a blue tone).
3. Pick out your brightest highlights with Fenrisian Grey and Corax White .
4. Shade panel lines with Nuln Oil .
5. Optional bring back some shadows on the armor plates with careful application of Drakenhof Nightshade .