Hi Dave,
I have mentioned it before but as it's you I will tell you. I start on the underframe with a mix of Humbrol matt black 33, matt khaki 26, and a bit of matt leather62. with all my underframes I pretty much just paint it on, once dry I sometimes add a bit of white 34, mixed with a bit of black and sort of dry brush in on though I tend remove some of it once I am done with a bit more 33, 26 mix. The bodys on the Grampus were a mix of 33, 26, some areas get a bit of 62 mixed in, once dry I tend to pick out a few bits with 62 as it's a good rust colour a bit of white gives it that faded look.
Hope that helps. Let me know if you want more info. I have posted a pic below which shows a business card which I have used to mix paint on a bit like an artist palette I go through heaps but they cost nothing.
Cheers Peter.