Have you ever seen directions that tell you to "pull threads to the back of the fabric" or the inside of your garment? You'll often get this instruction with topstitching, bound buttonholes, and machine-sewn buttons--or any place that you want to avoid backstitching and having cut threads on the outside of your garment. I used to be infuriated by this instruction because I had no idea how to do it. But it's actually really easy! Here's all you have to do.
I'll demonstrate on a simple row of stitching. This is the right side.
Turn the work over to the wrong side and pull up the thread tail. See how the stitch before it pops up?
Stick a pin into that little loop and pull it out.
Now both your thread tails are on the wrong side!