First, I sprayed a coat of krylon black lacquer as primer, then Alclad Aluminum II 'aluminum' - covering the wing leading edge areas and wing walk areas (and the rear faces and leading edges of the props).
Then I liberally dotted on liquid mask over the areas to be bare aluminum, using reference photos.
Next the main coat of Tamiya acrylic olive drab was sprayed on.
Then the liquid mask was picked off with a toothpick, that was also used to scratch off the Tamiya OD. At this stage the chipping looks WAY too contrasty, so the edges of the acrylic were picked back further with the toothpick, tiny dots of olive drab were added with a brush over the aluminum, and a silver Prismacolour pencil was used to further degrade the edge and do little dots and circles around rivets. And don't get me going on rivets - contrary to what some say, I think recessed rivets are what you want (e.g., Trumpeter C-47) - they create the illusion of rivets with the tiny shadows produced and their tendency to pick up oil washes.
This results in chipping that still looks too contrasty (I am sure you have seen this on some Jap models) - so the entire upper surface of the model (including the decals) was misted with light olive drab. This reduces contrast and creates the appropriate 'aerial perspective' so the model resembles a full sized object. The final overall coat of Testor's Dullcoat helps on this score as well - it goes over the bare Alclad without compromising the bare metal effect.