What you need:
A square of satiny or sheer fabric.
A styrofoam ball just too big to fit through the neck hole or a small wad of cotton batting and a rubber band
A spare doll head
A stick a little smaller in diameter than your doll's neck opening on the bottom of the head. Wood or Plastic, Black looks the spookiest.
Optional: White or Grey Wig
1: Place the Ball or Batting in the center of your fabric
2: Wrap your fabric around the ball or batting and rubber band closed to create a ghost shape.
3: Pull the Tails of the fabric through the neck hole of your head so they hang out the bottom.
4: Pull snug so that the ball you created fits comfortably in the head cavity. Sheer/Chiffon or Tulle works best for heads with smaller holes. I had to swap heads here because the satin I used was too thick for the other head.
5: Put the head cap back on the head to hide the ball inside the head.
6: Insert the stick into the neck hole, in the center of the fabric, to allow you to stick them all over your house in flowerpots or anywhere you can stick a stick.
I have yet to figure out a SAFE way to hang them from the ceiling, but if your doll head has openings for swappable ears, you can probably put string through there and hang them that way, but be very careful. I am not responsible for broken heads caused by unsafe hanging or forcing fabric or sticks through too small of holes.
Celebrate Responsibly!