A few questions:
1. Are you paying attention to the grain of the fabric of your base and applique? This can cause great puckering!
2. Also, are your fabrics of similar weights?
3. Are you using the same thread in the bobbin as well as sewing?
4. Does your machine pucker fabric when using a zig zag stitch normally or it is this special project that is causing pain?
I prefer something like interfacing or heat-n-bond. They come in various weights and are marvelous to use. They will also stay in place! :)
L