Along with a good 3view you will want to have some pictures or drawings of the specific aircraft that you are modeling. I'm talking THE aircraft with it's markings and proper pilot name, kill marks and other stuff like that. It's not enough to model just a generic type of model you want a specific pilot's aircraft and details of the markings. And get a good sized 3 or more view drawing. A little 2x3 inch 3view with thick lines won't get you any points. You want a proper documentation drawing that has rivet lines and sections on it so they know it's an actual P40 and not some generic shape with curved wintips...

Along with that it impresses the judges if you have a special ruler with you that has the regular inches for the model and a reduced scale that matches the scale dimensions of the drawing. If the model is 4x larger than your drawing the ruler would have a custom scale that is 1/4 inch to the foot so they can reference measurements between the model and the drawing without doing any math.

Other than that I think you may find documentation minimums in the AMA rule bookfor each class.