RE: Tips on the US National Insignia
I used to teach the Navy's Paint and Finish course in Norfolk. We taught the old fashioned way to lay out the national insignia on an aircraft. One of the things we did was make a "ruler" with holes in it at strategic lengths, so we could simply scribe the circle, the border, and all the stripes. Made life much easier. I must have graded hundreds of final exam boards, which included either a tri color insignia or single color insigina and letters, plus someother incidental stuff. I've actually, somewhere, got instructions for laying out most of Nato's national insignia.
Actually, you can find it on the web... MIL-STD-2161. Also has instructions for painting the US insignia, but I think just the latest versions. Haven't cracked that book in years....