The Spring 2014 issue of Windsock had an excellent article on how to achieve the correct colors and reflectivity on French five color camouflage. The technique described basically duplicates how the original colors were mixed. For the fabric areas, the article says to add 42% silver paint and the metal areas 42% light grey. The exact ratios of lamp black, prussian blue,chrome yellow,chrome orange,white,Alizarin red, Ventian red, burnt umber, and raw umber are all described in a chart. In addition there are color mixes for the proper shades for the national markings. I can not relate these formulas here because of copyright issues.
The only thing that I have to disagree with the article is the use of cheap acrylic craft paint. If you are going to spend alot of time and money on a model, you should use quality artist's acrylic tube paint. It might be possible to also use oil tube paints thinned to the correct consistency with artist's medium and some drying oils. I have many tubes of oil paint so I would like to hear from someone who knows how to transform tube oil paint into a type of enamel.