What I use.
At first, I use two additional layers, or waste layers, from top and bottom of the wood to scroll sawed. Just because I use enough thin wood, from 3 to 6 mm, these waste layers help me to make result more clear and sand less.
But I mostly work with hand fretsaw or jewelry saw.
As waste layers I use binding boards. The thickness of binding board is equal 0,5 mm, no more. You can use any suitable empty box from snacks, any empty box you have.
waste layers are glued to the wood and pattern sheet to the waste layer with natural rubber adhesive. I buy this glue in the special shops for shoemakers in my country.
adhesion is enough strong to hold waste layers on the wood and pattern during all scroll time.
After scrolling waste layers is removed easy. It is cheaper that any 3M product.
If you wold like I can make some photos of the process