First step, I draw the pencil lines, the most clean as possible. secondly, I scan it. In photoshop, I clean the lines with the rubber. Sometimes, I complete the missing lines with the tablet... Then I can start to paint !
Truly a beast. It coudl withstand damage that would bring down most fighters.
There's a story where a German ace slutes the pilot of one of these after depelting all of his ammo on it and still failing to bring it down. When the American managed to land, he started counting the bullet holes, but stopped when he reached 200.