Thanks for the kind words, friends!
B_R, here is the process I used. I generally use this (or perhaps with minor variations) on nearly every build.
1. Paint the model with the basic exterior colors. In this case, I used Modelmaster Acryl Light Gull Gray on the undersides, and Gunze Dark Earth & Tamiya RAF Dark Green on the uppers.
2. Next I used artist oils to add some general streaks and stains. The process is similar to the dot filter process described by some armor modelers. For the wings and tailplanes, I make streaks fore and aft. For the fuselage sides, I go up and down. I do a section at a time. For a wing, I'd first give the wing a light coat of turpenoid, which is an odorless mineral spirit-type mixture. Just a light brushing on, enough to get the surface wet. Then, using a toothpick, I randomly apply very small dots of white and raw umber oil paints. Then, using another brush slightly dampened and dried turpenoid, I being streaking the dots fore and aft along the wing surface. The goal is to get light streaks that mix and blend. It's better to go lighter at first until you get the hang of it.
3. Once that is dry (I usually wait half an hour at least), I do paint chipping with a Prismacolor silver pencil.
4. Next, I either hand brush or airbrush on a gloss coat. (I use Future.)
5. Apply decals
6. Apply another coat of gloss coat, at least over the decals.
7. Next, I use burnt umber artists oil & turpenoid to apply an oil wash to the panel lines.
8. The next step is what I call "post fading". It is an attempt to get the model surface to look like paint has faded. Most times you see this done to full panels. However, if you look at an aircraft's surface, it's rarely uniform by panel. More likely, the surface will look splotchy, with some areas more faded than others, even within the same panel. To attempt to replicate this look, I heavily thin a few drops of Tamiya XF-55 Deck Tan with a color cup full of 91% rubbing alcohol. I then begin to just randomly "scribble" the paint on with my airbrush, varying movement and distance to the model surface rapidly. (You WILL want to put a cover on your color cup.) I don't confine myself to panel interiors, but rather do this process over the entire model fully, until it looks slightly like it has the measles or some other terrible skin disease.
Also, I use this color to make an area of light exhaust stains. I prefer to make small up and down motions to make the stain look more jagged and random, versus the traditional method of forward and back.
9. Next I do "post shading". For this, I use approximately 1 drop Tamiya XF-9 Hull Red to 3 drops XF-69 NATO Black, and again heavily thin it with 91% rubbing alcohol. I then go over the panel lines until I get the desired look. I prefer to have heavier panel shading, but that's just a personal preference. I also use this color to fill in the middle of the lighter exhaust stains from the step above, again using the small up and down motions. You can also use this color to add in ejector chute staining, oil & engine staining, additional base for mud and dirt streaks, etc.
10. An optional step, which I did not do on this build, would be to follow up all of this with some additional oil streaks with artists oils, mud streaks with weathering powders, etc., and additional paint chips, etc., as needed.
11. I give the model a final flat coat of Vallejo Matte Varnish. This will "blend" in much of the post fading done in step 8. It will greatly reduce and diminish the work you did in step 8, so you'll need to experiment to see what your preference is. I can say if you saw my model before the flat coat, you'd think it looked awful, with streaks and blobs of the Deck Tan color all over. The flat coat really reduces the effect.
Keep in mind, I build a model every 2-3 weeks, so I have plenty of opportunity to experiment. (Experiment is another word for "screw things up!"
) This process works well for me, is very quick to do (I did step 2-11 on this model in three sessions Saturday and Sunday), and is easily reproducible. I did have several attempts that were either overdone, or underdone, as I evolved this process. So like anything in modeling, it may take a few attempts to get it to your liking. And if you're like me, you'll likely throw in a few twists and turns of your own. This method that I'm using is actually an amalgamation of techniques from several modelers whose work I have studied & tried to replicate & simplify.
I hope this helps!