Dave, I use a spray adhesive made by Elmer's, it is a repositionable mist glue. I spray the back of the pattern with this glue, then I leave it laying where it is for about twenty seconds or so for the glue to set-up. After the glue has started to dry just a bit, I then apply the pattern to the wood. Some people use painters tape over the wood, before placing the pattern. Personally, I've never found the need to do so, the pattern lifts off of the cutting easy enough for me. Whatever you do, don't apply the spray glue to the wood and pattern, apply it to the pattern only. If you do spray both, you'll have a very hard time removing the pattern from the cutting.
Len