Lay heart template on the front of chosen card, slightly off-center. Trace around it using the pencil; remove the template.
Apply sentiment sticker to the front of the first scrap piece of cardstock. Cut out around it, leaving a "V" tail on one side and a straight edge on the other. Layer this onto another piece of scrap cardstock and cut it out, with a small border visable around all sides. Apply this to the front of the card, straight edge overlapping the left side of the heart.
Using desired stitch, emphasize the heart shape by sewing around the outline on the front of the card. Tie off the string on the back.