My first step is making sure its a very "In-scale" black, in other words its an "off Black" or dark gray:
Here is a IMHO a good looking Corsair where the author used Black mixed with Red Brown:
http://hyperscale.com/2009/features/f4u5n48ir_1.htmCompare to the real thing (which is parked outside, so may be more "faded" than was the case in service):
I also REALLY like this BF-110 though. It looks like it was panel shaded in various colors:
http://www.panzer-bau.de/flugzeuge-1-32/me-110-d-nachtj%C3%A4ger-final/Seen many 160th aircraft up close and they are very much a dark dark grey with many shades and panels:
The Chinook demonstrates it well because its large size is a shows the variations well.
Remember when adding a gloss coat that is permanently darkens the color, so take that into account.
Looking for more articles and other tidbits but this is what I have so far :)