This is more about the philosophy behind what we're doing, than actual DOING, but since this is about really understanding what's going on, it needs said.
The EPS is based on PROPORTION. That is the great thing about it, as well as the potential problem. Everything is a fraction of the body circumference, also called (in various books) the key number, or the 100% figure. Once you arrive at the correct figure, you can play around with it quite a lot. But if you blow this first part, nothing's going to come out right, ever after, amen.
To get the figure, lay out your prototype. Don't stretch it or anything silly, but smooth it flat, on a flat surface. Measure it from arm pit to arm pit, and double the figure. Make sure you measure straight across and not crookedly.Write down the figure you get.
Now. Once you've got your 100% figure, you CAN start knitting. Cast on some kind of edging and let it rip, on up to the armpits.
However. (There's always a however, isn't there?)
Look at your prototype. What do you like or not like about it? Does the bottom edge suck in to a ribbing that makes you look like a mushroom? Does it drape out in an A line? If you like the way the bottom edge works, measure it too, and hang on to it for our upcoming step involving math. If you don't like it, figure out what it takes to make you like it (what kind of edging do you want on the bottom hem?) and jot it down for the horrifying math part.
Traditional edgings include:
-The Usual Ribbing Edge: casting on 90% on smaller needles, working some kind of ribbing, increasing to 100% at the end of the ribbing, changing to the regular needles, and knitting up from there
-Hem: casting on 100% on smaller needles, knitting an inch and a half/3cm of stockinette, working a purl fold round, switching to the usual needles, and knitting from there; the raw stitches of the cast-on are either worked as a knit-in hem or stitched down later
-A Line: casting on up to 250%, working a hem or ribbing, then decreasing down to 100% gradually over the bottom portion of the sweater until the arm pits are reached (this method uses an ass ton of yarn)
Your homework for now is to measure your prototype, get your 100% figure, and then decide what kind of bottom edge you want. I'll be doing a hem.
FYI: I suggest a notebook or a document on your computer, or some other single spot to write all this stuff down. We've barely started with the measurements and math and figures, and trust me: you lose your plans halfway through the project, you're in a world of hurt. I've been there. It sucked.