I actually always use the same techniques ... in this case I just stripped it (a mistake), washed, two coats of primer, the painting was done with spray painting (blue), after that I used small pieces of sponges (the type of dishwasher) ..
The colors (tamiya) that I used were brown, orange, gray, matte black, gloss black, silver, the Wash I did with nankim black diluted ....
In some points, I use the tamiya diluted with solvent to give this effect ink drained.
But I still have not finished this part of the painting, will now apply the oil paint and a bit of graphite powder....