The pattern I'm working on now is the 1930's coat/dress that I posted a picture of below. Some of the pieces are so fragile they shatter when I touch them, but I think I managed to make an accurate enough copy first. Now I'm working on less fragile pieces (phew...).
I've read tips and trick on the internet that you should iron your vintage patterns before copying them, but for me that's a big NO! The heat will accelerate the deterioration-process that is inevitable, so instead I try to flatten them as much as possible by carefully unfolding them and placing my rulers on them when making the copies.
If they're very scrunched up (this one was, partly...) I use moisture instead of heat. You can use an ever so slightly damp piece of cloth and gently press the creases until the fibers straighten. Too much moisture will damage the pattern too, but it works pretty well. I got that trick from my mum who works in an archive... I trust her more!
I've made photo-copies of the instruction-sheet and envelope to preserve the originals that are very brittle too. Weighing the pattern-pieces down by placing rulers on them works pretty well and is a big help, otherwise they seem to walk around by themselves!
Loads of little marks and punctures to copy.... I'm intrigued by the system, and since I use chalk-crayons to mark up the material when I sew I think I'd actually prefer this system to modern printed patterns. I don't punch the copies though...