Mike, I think you answered your own question. There is no "one" way to do it. But with paint of course, one starts with the lighter colors first. I also know you are not using paint.
"Not using paint?" OK.
Yes, generally light colors are painted first, but much of that can depend on the type of paint and it's covering abilities.
This camo job I'll do on the Mig-3 will be done a tad differently.
Obviously, I'll apply a thin light base coat of white, just enough to cover. I will then "hard" mask the soft lines you see in the graphic separating the main colors. Most likely, 3/16" or 1/4"?
I can then mask on each side of this tape to paint the required colors. There aren't many.
When done, you pull all the masking. What's left is the desired colors with a hard edge of white between the colors.
Fine sandpaper to knock down the edge, then a quick air brush with white paint, at the right distance, will soften the edge and should give the desired results.
I can't think of an easier way.
Charles