For the tripod headstand DO NOT PUT YOUR WEIGHT IN YOUR HEAD!!! Very very dangerous thing that most people do. YOU COMPRESS YOUR NECK WHEN YOU DO THAT. Trust me - you do not want a broken neck.
Your weight should be in your hands, as though you could push up into a handstand from that position.
The headstand in the picture is a tripod headstand, not a regular headstand. The neck thing applies to both.