I'm making the short sleeved version, without a collar, and using a striped fabric. And that's where my miseries began.
First, although I was very, very careful laying out the pattern, when I went to sew the shoulder seams the stripes lined up on one shoulder, but not on the other. Quelle misère! I wept, I swore, I sat in the back of the closet sulking for hours, until I decided to live with it. (And I don't want to hear any more helpful suggestions like covering it with epaulettes. I mean it, both of you!)
So on to the facings. I very carefully lined up the stripes along the edge so they matched, assuming (foolishly) that they would still match 5/8" of an inch in. And they didn't. And it matters, because it will show when the facing folds open at the top.
At least, unlike the shoulder problem, this could be fixed. Here's what I did, after ripping the beastly thing out:
I pinned the bodice piece to the cutting board, lining the edge up straight, marked 5/8" inches several places, and then chalked a single line across.
Next, I creased the line with the hera.
Pressed it flat.
Now I was able to see exactly where the stripes were at 5/8" in, and I carefully pin basted it.
Next, I machine basted it, just to make sure, and finally I sewed it for real. And it's perfect! And I'm a perfect wreck.
Absolutely essential tools: seam gauge, chalk wheel, hera and straight edge.