Hi Monte!
I first painted the kit overall in light grey. Then I masked some panels using Tamiya Tape and put some pastel powder on them. I used white, grey, black and brown pastels and sometimes mixed them together. It's not that time consuming, but you use a lot of masking tape!
After this treatment, the panel effect looks overdone and the plane "dirty". Don't worry about it, just put another layer of the light grey. But this time the paint must be heavily thinned, translucent and have a milky appearance. Paint until you can barely see the difference beetween the panels!
Then I spray some Futur (Johnson's Klir in France) at voilà! Le tour est joué!
By the way, I used Tamiya acrylic paints!
Hope this can help!
Jean-Luc