Well, gee... Since none of the other skinners are going to say anything, I guess I'll take a crack at it.
You've added a lot of "paint chipping" (I'm going to call it that, not sure if you call it that) with a light grey-ish color. This chipping all seems to use the same size brush, and on the side of the fuselage you can see perfectly round dots where you clicked onces. Paint won't chip in perfectly round circles for no reason.
I would start out in a harder brush, with a smaller brush size (half the size of what you used). If you want to cover the same size as the other brush, just use twice as many brush strokes to fill it in.
Then, when you're done with that layer I suggest duplicating it, hiding the original, and blurring the frak out of it. Say, a guassian blur with a 3.0 value.
Just for kicks and grins. You might like how it looks. Try different values.
It looks too uniform, too much like brush strokes right now.
Also, consider using a "cloud" layer. This is basically creating a new layer, selecting a dark color and a light color (forground/background -- try black/white) and filter > render > clouds. Take this layer, put it on top of every other layer, and reduce the opacity and play with the blending. You want the end result to just barely be visible. You want it to break up the solid patches of color you have with the "cloudy" variations.
Weathering is the tricky part. Even I am limited in what I can "pull off" so to speak. I was hoping the folks that are way better than I would chime in.
