I started out using freezer paper for applique. You take a couple of layers of freezer paper, glue them together, cut them out in the shape of your applique. Then you use it as a template for turned-edge applique, you brush the edges of the fabric with starch and iron it. Here's a video:
https://youtu.be/G8VAENGWQ1Y
However, I found that the paper quickly became soggy, no matter how many layers I used and how careful I was, and I was unable to get crisp, sharp edges. So I switched to Templar heat-resistant template plastic. That stuff is the bomb.
I use freezer paper for patterns, especially for things like blouses. I copy the pattern onto freezer paper, then iron it onto the fabric. No more pinning.