Guidelines, including a video, for donating hair are available on the organization's website.
From the website:
WHAT IS LOCKS OF LOVE?
Locks of Love is a public non-profit organization that provides hairpieces to financially disadvantaged children in the United States and Canada under age 18 suffering from long-term medical hair loss from any diagnosis. We meet a unique need for children by using donated hair to create the highest quality hair prosthetics. Most of the children helped by Locks of Love have lost their hair due to a medical condition called alopecia areata, which has no known cause or cure. The prostheses we provide help to restore their self-esteem and their confidence, enabling them to face the world and their peers.
Our mission is to return a sense of self, confidence and normalcy to children suffering from hair loss by utilizing donated ponytails to provide the highest quality hair prosthetics to financially disadvantaged children. The children receive hair prostheses free of charge or on a sliding scale, based on financial need.