I have two different designs that I incorporate in my models.
The first is black base coat, dry brush chain mail on joints and chest piece. Then I paint the armor pieces shining gold. Not the entire model, just the armor pieces, wrist guards, forearm armor, shoulder armor, leg armor, and shine guards. Then this is where I have to choose. Some I paint the face mask shining gold, then others I paint the head chain mail. The chain mail ones I call part of my eternal patrol squad and have them with weather effects, but not the shining gold armor. Then I have the gun the standard black, with snot green for the energy feeder. I put a coat of gloss on the energy feeder and paint the very bottom of the blade shining gold. This makes the blade seem ultra sharp (mainly because you can't see the gold is is reflecting so much). Then I painted the entire insignia shinning gold, then picked out the symbol with mithral silver. I'd say my necrons are worth quite a bit on the black market. Make a couple million off the gold alone.
I was going for heroic necrons, while they don't seem that way, they do seem stronger and immortal. They also partially blind anyone that stairs at them and is within 6 yards.