When I paint historical models, the first thing I try to do is a little research.
The Torpedo 508 CM was used in the Italian Army during WWII as a general-utility vehicle and, occasionally, for recon (being a rugged and fairly fast vehicle); thus, I checked the Italian Army website and in the section dedicated to its history, I found just what I needed: a picture of a restored vehicle.
The bonus is that the picture is actually in colour, while all the period images I had found were in black-and-white, so I can use this to actually understand the colour scheme.
Having this quite clear in mind, I started preparing the models for painting: the castings were excellent, with nice, crisp detail and only the tiniest bit of flash or mold lines (which were removed easily). I then washed them in warm water using a little soap, so that I could take any grease off them. Finally, I undercoated them using black spray paint and affixed them with a pin to a couple of spare flying stands, so that I could handle them while painting without having to touch them with my fingers.