I recently finished making a 3-d bow tie for my niece's graduation. Since I am still working on the back the only thing I can show you is a not so good pic of the wrinkled top. I pined all 3 points. The middle where the seams met at at each end of the dimensional middle of the block. I found that pinning made it much easier and my accuracy was close to perfect on each block. Here is a link to a good video:
https://www.youtube.com/watch?v=BVdfuGgtHf8 . Here is a pic of the quilt I am still working on.