Here's a technique I developed a while ago and have used several times since: creating shapes with ribbon and/or fibers. The key to its success? Strano Ribbon Stiff.
To create a ribbon heart, you will need the following supplies:
pins, Ribbon Stiff, ribbon, and a foam block (the one used here is from some decorative brad packaging)
Next, you will cut your ribbon to the desired length (practice making the rough shape first), and coat it with the ribbon stiff. A foam brush helps!
Once this is done, pin your ribbon down at the dip in the heart (fold the ribbon in half at an angle and pin).
Next, shape your ribbon into a heart, then pin at the bottom.
Now let your heart dry, then use it in your next project!