I began these English paper-piecing Grandma's flower garden pieces a couple years ago - fun take-along project.
One 'trick' I learned at a meeting is to punch a small hole w/ hole paper punch in middle of each paper & use short straight pin through hole to keep fabric in place while hand-sewing.
Also, until each petal is sewn to another on all sides, do not remove the cardboard form. Maybe you already knew this, but just in case...