Hi! I would like to know your tips and techniques on how to simulate extreme faded paint, especially, on Vietnam SEA Camo pattern. As far as I understand, you either lighten up all the base colors - in this case I used a 3-color camo or use chalk pastels? If i already painted the kit, now I have to mask again to lighten each of the base colors? Thanks.

If you have an airbrush, you need not mask again. Lighten the camo colors about 20-30% with white and thin about 50%. Then spray the areas, starting in the middle of a panel and working towards the panel lines and edge of the camo pattern, but don't go all the way to the line or edge. After you have finished that color, lighten it again about 20-30% and thin it to about 75% thinner and lightly go over the color again to blend everything together. Repeat this with all of your colors. You may even want to overspray the entire airframe with a higly thinned tan (about 90% thinner) to blend everything together. Remember that the horizontal surfaces will fade more than the vertical surfaces.

That's my method, others may have different ideas. . .

My technique for fading paint is to overspray all upper areas, or those that would catch the sun or be faded which ever way, with very heavily thinned medium sea grey (an RAF Colour). I spray this over decals as well, 'cos the markings would fade also. Before spraying this I give the model a coat of Klear (Future in the US). Here’s a desert Spitfire done using this method:

Also my F4U-1 HERE had similar treatment, but the metal and fabric areas were differentially weathered (as were the markings).
When spraying the MSG (Medium Sea Grey) try and not to make it to uniform. The more fading you want the more you overspray. I tend to spray in 1/2" (give or take a bit) bands, overlapping some to get a denser effect. The Spitfire was my first attempt at this and is, possibly, a bit to even.
Mal

my techniq is to paint the whole model with lighter shades paint first (color +20-30% white). then paint the model using the original shade of paint (no added white). give emphasis on the demarcation lines between two colors.
here's my model...