I pinned them to keep them lined up. One of the only times I've resorted to pinning, but with the non-nesting seams, it was the only way to keep them were I wanted them to be. Other than the center, didn't think it was bad.

I'd start sewing the seam, then stop with the needle down, fold back at the seam I wanted to line up (just 1/4") and make sure it was OK, then pin, sew to that point and then check and pin the next matching point. For the really tiny ones, I wasn't as particular, but tried to get it the best I could. But when they are that little, you don't have much fabric to work with to ease in any differences. I probably ripped and resewed about 10% of them, mostly the smaller ones. I thought that was pretty good.

I completed Carol Doak's 50 paper pieced stars, and some of them got ripped and resewn multiple times. I had much better results once I started removing all the paper before sewing things together, even though the book says not to do that.