Painting the cockpit or dusting the upper/exposed surfaces with Tamiya's Rubber Black (my new favorite black) could help simulate sun fading. Otherwise, you're 'chipping' the corners with little dabs of light gray or flat aluminum to simulate where that black paint has been chipped off.
You could also use different 'gloss' paints, like flat overall with some semigloss in some high wear areas. Or even purposely paint a section with a layer of paint with a brush to simulate a 'repair' that needed touchup in the field just because you _know_ the Airman who's ordered to 'fix it!' isn't going to spend a lot of time making it look pretty.
Gene Beaird,
Pearland, Texas