take your time, dont worry about rushing it. if you neatly cut and score every piece like you should. then properly glue it with the glue of your choice, then you shouldnt have anything to worry about when making your armor. i personally started with a helmet and well learning with a challenge is a great way to start!(and who doesnt wanna just wear there helmet whenever they can, i know i do ) so good luck and if you have any questions, well..look at the stickies or you can ask me in a PM. also if you look to the top of the page..yeah up there. there is this nifty trinket called the Search button. it's a godsend when you are lost.
Live Long and Prosper
use the testers. they will save you from making mistakes. you do not want to make a fancy one and then its too small or something. thats what i did. i made an hd handplate of robos and it was too big, so im making a tester right now. not too big of a deal since it was just a handplate, but it would have been nice to not have to redo everything. good luck.
If your a total PEP noob like me, start with somehting easy. I started with the forearm. Basically I did all the small things first, now I'm moving up to the more advanced things. Like it was said, take your time. From what I can tell so far, these things almost put themselves together, and are alot more daunting to look at than to do.
My first pep piece was danni's helmet. I didn't change the scale or anything and it fit me perfectly (a little tight around the ears, but some sanding will fix that). Don't do that. Measure yourself for whatever armour piece you start with, and scale accordingly.
I would recommend dowloading Robogenisis' simplified MKVI pack, and trying one of the smaller pieces, such as the hand plate or boot (just make sure you don't get the high-def versions from his other thread, because those are very newbie-unfriendly).