Here is a great video on how to fall out of headstands and handstands:

http://www.doityourself.com/video/Off-the-Wall–Falling-Through-Head-and-Handstand-79727561

The wall is a prop. Eventually, you are going to want to be able to practice inversions in the middle of the room. We will all fall at some point; the trick is to know how to fall safely out of these poses to avoid injury. Patrick from the Yoga Garden says, “When we fall, we need to somehow transfer the energy into motion, rather than a jarring shock to our bodies.”

Basically, in Salamba Sirsasana (supported headstand) fingers threaded behind the head. If you fall, release the fingers and with palms open, tuck your neck, bend your knees and roll out of it.

In Tripod Sirsasana (tripod headstand), you can’t tuck your neck, so fall into bridge pose with your feet landing first.

In Ahdo Mukha Vrksasana (handstand) fall into Urdvha Dhanurasana (full wheel) if this is a pose that you can do. Keep arms long and head off the floor, trust that your legs will catch you.

Remember: Everyone falls. Learn to roll; don’t fight it! Practice falling at home. Relax and don’t panic. Stay limber and loose so that you can dissipate the energy and avoid injury.