Did you guys even read this faq? If you still don't know how to scale, then I suggest you start back at page one. Its pretty easy. Scaling is the key to Pep, I suggest that you become very comfortable with Scaling and understanding the measurements it gives you. then you can measure yourself and adjust to have the armor fit you nicely. I suggest making a few pieces a few times till you know its going to fit you just right. Plus that will help you get better at scoring and folding and putting out some outstanding armor.
I'm just trying to help as always. If everybody came in here asking exactly what to do and everybody told them every single time, then nobody would bother to take the time to actually learn. Putting the time into this site and searching for things and browsing old forums topics, or hell just reading the stickies will answer 99% of your questions. I can't speak for everybody, but when I invest the time and effort that a project like this requires I like to know at the end of the day that what I've created isn't just a "copy" of somebody else. Plus, by learning how to use the tools you have to create this armor, you just might actually help somebody out one day. If caring about all the hardwork and time and posts that's gone into this site to help people is being a jerk, then I guess there's a lot of great jerks on this site.
What I'd do is to measure your head with a tape measure, make sure you know what it is in cm.
In pep it tells you the Height, width and depth (which is from the nose to the back of the helm) of the assembled model. Take the Height Width and Depth of your own head and of course give some room for a liner and such and then play with the scale by inputting some similar scales. I'd start by going down in scale from the original. Everytime you put in a new scale it will automatically update the dimensions in the bottom right hand corner of Pepakura. You can do this with every single part of the armor to custom tailor it to fit you nicely. I suggest printing an assembling your "test scales" till you find the right one. It does take a little longer, but you'll get that custom fit that will look nice as a finished product. I know since I have started, I have built 2 different biceps, 3 feet, and a couple of calves. Good thing is you only have to do it for one side of your body, then mirror the scale for the otherside. Be careful and take good measurements for your chest and waist and head! Those are pieces you dont want to build to many times!!! Hope this helps!