Using a leave in stabilizer such as Pellon Fusible Fleece behind appliqué pieces makes for even stitches that are anchored nicely to the piece.
Use Pellon Fusible Fleece As A Stabilizer
Pellon Fleece Fusible 22 in. x 36 in. White
Pellon Flex-Foam: Sew-In vs. 1-Sided Fusible – MOORE APPROVED
All About Bag Interfacing - Sew Sweetness
Pellon® 973F Heavyweight 1-Sided Fusible Fleece. Color: White. Size: 45 x 10 Yards By the Bolt. It's suitable for home decorating, apparel,
Pellon® 973F Heavyweight Fusible Fleece Fabric, White 45 x 10 Yards by the Bolt
Use Pellon Fusible Fleece As A Stabilizer
Pellon 15 x 36 Peltex Ultra Firm Sew In Stabilizer, Pellon #70PKG
Pellon 809 Decor Bond Fusible Stabilizer 45 inch x 10 Yards White
Pellon Peltex 1-Sided Fusible Interfacing-White 20X10yd