I made this tutorial for mitering corners when using bias tape to help out a friend (which is why there's a cat nose pictured), but I thought I would share it in case it could help anyone else. I know there's other tutorials out there, but it helps to have options!
I had to learn how to do this when I made my Miyako costume ([link]
) back in 2010, which involved 32 mitered corners. Here's a progress photo of some mitered corners in action: [link]
If anyone has any questions, I'd be happy to help! Happy mitering!