I use Sharon Schambers basting method. it take a bit more time but is more accurate AND it can lay around for some time with no shifting. She has videos of how to do it. I hate pins and gave them up and went back to thread basting. There are 2 videos that show..
https://www.youtube.com/watch?v=bhwNylePFAA This is my preferred method.
If you must use pins. here's a help too:
https://www.youtube.com/watch?v=jnke_KzeTI8