I've seen a couple of your works, and what I'm wondering about is the resolution you are working on. The feel of the panel lines suggest 1024 res, but the markings are pretty much fuzzy, and that's why I'm getting confused.
My guess is that you work with larger markings and then shrink them to proper size. If it is so, this is a must-avoid when skinning aircraft, because reduction of size fades out the borders with anti-aliasing, and the end result is that the markings look pretty awful.
The best way is the long way around - make your own markings, and start at the proper size from the beginning, so you don't have to enlarge or shrink to the proper surface. This also means the same markings for wings, tails, fuselage etc.. must all be separately made.
The shadows you gave to moving surfaces at their adjacent borders is a nice touch, but like Krusty said it could be a little bit overdone. Perhaps a little adjustment in opacity would be preferable.
Finally, the green undercoat, underneathe the winter white, seems to be a bit awkward in color. That's probably because the profile pic you used is a bit off in color.
Ah, a final tip - when taking screen shots, always put your plane at an angle where the sunlight shines down - dark and shadowed surfaces make it pretty hard for fellow skinners to comment. You can change the time at the arena settings so the sun is at a different position.
