Well, let me share my process, with some hints about what I think it's most important. Please, bear in mind I'm a complete newbie.
Below it's the setup of my "workstation"
1 - Cutted templates. I always keep them around, in the case of doing something wrong and have to re-do. After a piece is glued and ready, I put these templates inside an identified envelope (for example: "Iron Man Mark VI chest"; "Iron Man Mark VI forearm"...) for future use (in the case I'll want to build again...).
2- Work area. It's where I draw the templates over the EVA foam, where I cut and where I glue. It's where I almost fall asleep, if I do this by late night....
3 - My faithfull friend, the hot glue gun
4 - An old newspaper. My glue gun drips, and it's a very bad idea have your table full of glue spots (specially if you are married). I keep this piece of paper there, so the glue gun can drips and you save your head from decapitation from your wife. :love
5 - My other faithfull friends: cutting tools. I use a scissor, basically. X-acto knife? Sorry, didn't find one to buy around and don't want to place an order for one.
6 - Large pieces of foam - flaps from the foam cutting process. Usefull for repairs ou filling gaps between spaces.
7 - "Garbage can". OK, that's a sack, not a can. Use anything to put your trash inside ans save you from the rage of your wife. :behave
My files are from:
http://www.therpf.com/f24/robo3687-iron-man-mark-4-6-pepakura-128147/
About scaling:
I read the hints at
How To Scale Your Pepakura Armour-Tutorial.
However, I adopted other method I've read somewhere here, which consists of a) printing templates in common paper b) joining them (I used tape) c) wearing the piece and verifying if it's OK.
If the piece it's OK, I still add about 15mm in the width (considering the thickness of the foam I'm using - 5mm x 2 with a bit of space added). Using Pepakura Designer 3 for scale adjusts. It's a labor-intense method? Of course! But it is much worst re-do after you have the entire foam piece ready.....
It's very empiric, I know. But it works, you'll see. :lol
For cutting and glueing, I love this post, it helped me a lot
http://www.therpf.com/f24/foam-speed-building-filesntricks-spaceballs-darkhelmet-added-148889/