Here are the rest of my tips for tracing pattern pieces from your Japanese sewing books.
Tip #6 - No need to go crazy. For the first pattern or two that I traced, I was really worried about complete accuracy. I ironed the pattern paper (low iron, no steam) and taped my tracing material on to the pattern sheet. I'm still pretty careful, but I find that smoothing out the pattern sheet with my hands and using a spare ruler to hold down my tracing material works just fine. I don't have any pattern weights yet, but that would probably work great, too.
Tip #7 - Take a look at the cutting diagram. I hardly ever do this for English patterns. For the Japanese patterns, it's more to figure out which pieces I need to cut out than anything else. Here's an example of one:
So I can see from this that I need to cut out a back and a front, 2 sleeves, 2 collar pieces, and a long strip - probably some bias tape or neck facing.
Actually finding the pieces can be quite challenging - like "Where's Waldo" but worse. So far, in my experience, once I find one piece on a page (most of my books have come with 1 or 2 huge pages of pattern pieces on both sides - so, at most, you only have to look at 4), the rest of the pieces are on that same page. If your cutting diagram has some long, rectangular strips, you won't necessarily find them on the pattern sheet. You can see from the diagram above that the pattern calls for 2 strips that are 3 cm wide. There's probably a length measurement that I cut off in the photo. We all can cut a rectangle without a pattern piece, so it's probably just as well that they're not included in the pattern sheet. I have only one pattern for a skirt with a waistband that did have the pattern piece - probably more for the button placement than anything else.
Because there's so much overlap of the pieces, you really have to find one line . . .
Then sort of trace it all around with your eyes (and eventually your pen/pencil) to figure out which piece it is and where it starts and ends. You can see that instead of having a big fat letter in the middle of the pattern piece, there's just a relatively small letter pointing to one of the lines. It's pointing at the 130 size line, so if you're not making that size, find the closest line to the size you are making. You can see the 100, 110, 120, and 130 that this pattern came in in the photo above.
One thing these patterns do have in common with English patterns is that they do use a letter to represent the item of clothing that you are making and luckily they are English characters. In this case I was tracing the sleeve for shirt pattern "H".
The other reason to look at the cutting diagram is that all seam allowances are not created equal. I only just realized this recently. See the little "2" near the center bottoms of the sleeves, front, and back? That's telling you to add a 2 cm seam allowance there instead of whatever you've been using. If it's not indicated in the diagram, then you just use your regular seam allowance. You can also see that it's telling me to do something funky with the bottom of the piece on the left. (I haven't quite figured out what to do yet, but it looks like I need to add 3 cm on the left, and cut a little rectangle out of the bottom.)
Tip #8 - Watch out for pieces inside pieces. I recently made a shirt where no matter how hard I tried, I couldn't find the back neck facing piece. I finally decided that I would just trace the neck on the back pieces and just cut a few inches below the back line. As I was thinking about how I would do that, it occurred to me that I had seen the exact same thing on the pattern piece for the back. There was the back piece which I traced then inside of that - right where you would sew it - was the back neck facing piece. I know that would make much more sense with a photo. I'll try to add one tonight.
The other tricky thing is that sometimes you can make both a dress and a shirt with the same front and back pattern pieces, so even when you've found the right piece, make sure you're selecting the right length.
Tip #9 - Pay attention to the symbols. There are a few different indicators to tell you where to cut or where to place a button or a pocket. These are on the actual pattern pieces (not in the cutting diagram). I think the symbols are pretty self-explanatory, but you sometimes have to really look to find them. Because there is so much overlap of all the pieces, it can be really hard to see all the different pattern markings. I try to take a look and get an idea where they all are in a certain piece before I lay down my tracing material - just because they're a bit easier to see that way. (I still forget sometimes. Sometimes I even have to whip out the whole big-butt pattern piece while I'm in the middle of sewing because I just know there should have been a mark somewhere that I didn't make.)
The most important one is the dashed line. They're pretty big dashes, so you might not notice at first, but this indicates a fold line. If you cut on this line instead of placing the piece on your fabric's fold, that's a pretty much unrecoverable mistake. (I suppose you could sew them together with a small seam.)
The other really useful one is a little tick mark with a circle at the end of it. These are the equivalent of the little arrows you see in most typical patterns written in English. Those little arrows that are such a pain in the butt to cut out. For Japanese sewing, I just cut a little snip into the fabric's seam allowance wherever I see one of the little tick marks then line up my snips instead of lining up the arrows.
Here's an example of what they look like:
This happens to be the top back of a sleeve. You don't have to mark and snip all 8 tick marks. If you look closely, you can see that there are two for each size. You only have to mark and snip the 2 for the size you're making. Don't forget to bring them out to the new line you're drawing with the seam allowance.
These little tick marks can appear anywhere on the pattern pieces, but they're almost always at the center, back, and front of a sleeve - the top curvy part - with corresponding ones on the front and back body pieces - the armpits. The two tick marks usually indicate the back of the sleeve and the single one indicates the front.
Some other common places you'll need to mark are pockets:
(See the lighter colored dashed lines? These are where you'll place your pocket - not fold lines in this case.)
And buttonholes.
(The one on the top is the same for all sizes. The bottom one is slightly different for each size. You'll obviously mark the one you're making.)
The line with arrows on either end is the grainline, just like in most U.S. patterns.
Tip #10 - Label your pattern pieces. So there's not going to be the nice little directions that come with U.S. patterns, like "Cut 1 on fold" or "Cut 2 fabric, cut 2 interfacing" or even "bodice back" or "sleeve", but you can certainly provide those labels yourself - after all you worked so hard to figure it all out. I usually write the name of the book (which I sometimes make up if there's no English name on the book like "Bubble Dress Girl"), the letter of the pattern, the pattern piece, and the size. Here's a sleeve pattern piece all cut out.
I should mention that I don't precut all the pattern pieces. There's really no need to do that. I just trace them then when I get ready to cut the fabric, I just sloppily cut around them enough to free them from the rest of the pattern pieces, then cut them at the same time as I cut the fabric. I know that probably doesn't make much sense. I'll include some pictures when I do a post about cutting the fabric - hopefully tomorrow. Just know that you don't have to neatly cut all the pattern pieces out of your tracing material.
Tip #11 - Keep your patterns organized. You've already done a ton of work and you found some nice, durable tracing material, and the patterns are just so darn cute that you're probably going to want to make the same pattern a bunch of times. Or better yet, combine different pattern pieces to create a completely new design. So you might as well keep them nice and organized. I bought a box of these big envelopes at Staples two years ago when I was doing virtual quilting bees. 
It was nice to have the envelopes on hand back then, but they've also come in really handy for all my pattern pieces. I try to use one envelope per pattern, per size.
Whew! I hope this is all helping. I didn't expect to have so many tips about tracing the pattern pieces. I'm not sure I'll have so many about the rest of the process, but this is probably the hardest - and least fruitful - part.
Don't hesitate to post a comment or shoot me an e-mail if you have any questions.
