A handy guide to working on your handstands, via Carl Paoli and Gymnastics WOD:

Handstand against the wall progressions:
Part one: In this video, Carl explains why practicing Handstands with your chest against the wall is better than with your back against the wall.  Carl demonstrates ways to get into, scale, and balance the handstand with chest against the wall that is otherwise not possible with the handstand with back against the wall.
Part two: In this video, Carl demonstrates how to use the Handstand with chest against the wall to assist and build your freestanding handstand, as well as how to bail safely with a Forward Roll.

Handstand forward roll progression:
In this video, Carl demos the progressions for the Handstand Forward Roll, by combining and scaling elements from the Kick Up to Handstand, the Handstand Push Up and Handstand Push Up Against the Wall, and the Forward Roll.

Handstand practice and spotting:
Part one:
In this series, Carl will demonstrate, with Adam’s help, some ways to develop your handstand by yourself and along with a partner to help spot you. In this video, Carl shows you that the key is to allow your body to develop an awareness for new overhead positions, along with a progression that will help you overcome the fear and awkwardness of these new positions when you’re upside down with your head inches away from the ground.
Part two: Next, Carl and Adam demonstrate how to do partner spotting to help guide the athlete to tuck up to handstand. The tuck up is a key drill to work on solo and with a partner, as it helps to train you to always lock out your arms and push away with your shoulders.  Only then will you feel like you have a solid foundation with your hands to the ground to be able to extend your legs up into a full handstand.
Part three: In part 3, Carl helps Adam find control with his handstand with another spotted exercise. As the spotter, make sure you help the athlete feel secure to get them safely back to their feet while you progressively move your spot & support down. As the athlete, focus on maintaining core stability and finding your balance as the spotter transfer more control to you. This will likely take more than a few tries, so communicate with each other when you see or feel any breakage in positions that needs to be fixed on the next attempt.