Hello guys, thanks for your comments.
I made the dusty effect with three techniques, first I used oil paints, put many dots of oil paints of different colors (brown, light brown, yellow, white, etc.) over all the plane and blended with a wet brush, dragging in longitudinal direction over the horizontal surfaces and vertically over the vertical surfaces. I did this until I have a very subtle effect. This makes a general dust and rain marks effect.
For the second step I used the “splash effects” of Ammo Mig. Used “Dry earth” diluted, put some on the zones more dusted and blended with White Spirit.
And finally applied some pigments on the most dusted zones.
For the wheel spats I used again the “splash effects” mixing layers of “Dry earth” and “Loose ground” and finally diluted “Dry earth” blended vertically.
The sliding canopy is the worst part of the kit, because the sliding part and the fixed part are e single piece. What I did is mask from the inside and from the outside this part. I masked from the outside the frame of the sliding part and from the inside the frame of the fixed part, so it makes the effect that the frame of the fixed part is behind the glass of the sliding part.
Luckily the piece has the frame of the fix part marked in the inside and the sliding part marked on the outside.