Place your palms on the ground and the crown of your head in front of your hands close to a wall, forming a triangle with these three points of contact.
Flatten your back against the wall and lift your legs up until your feet are against the wall.
Put some pressure on your hands for stability; don't let your head take all the load.
Risks
This exercise puts a lot of pressure on the head. Make sure to warm-up your neck thoroughly before starting.