I'm still far from finished but working at my own little pace...
This is what I did :
1) paint the whole model aluminium with ALCLAD paint
2) cover some areas with MASKOL
3) paint the top surface IJA green
4) prepare a lighter shade of green and spray it on the top most surfaces
pictures at that stage :


5) a few days later, rubbing the model with my fingers, I peel off the maskol
pictures :

here, I'm pulling on the maskol :

the result :

The green is Tamiya paint : acrylic.
Now I soak the green parts with spirit, and with a fine brush I place small dots of light green and dark green
oil paint (artist oils). With another brush, I pull these backwards, following the airflow.
That way, I have streaks and different shades of green... I want the green to realy look worn out !
result :

Then came the masking for the black parts :

I know I went too far with the aluminium, but now it's done... I'll try to tone down the big surfaces a bit... and I'll add plenty of small scratches !
So, what do you think ?