|We were unable to find the source for this photo...anyone know?|
1. The key to getting the "beheaded" look is to be able to see the body's neck. Taking the photo more from the side rather than from the feet will get a better angle to improve the illusion.
2. When you take the picture from the side, take it from the sunnier side. I know you'll have to try and hide your shadow, but by taking it on the sunny side you'll minimize how much the mound of sand over the person's head stands out.