It takes a good qigong teacher or qigong coach.
It is a good thing if he demonstrates his skills.
This may be a video clip in the internet, a demo DVD or a public appearance.
Besides general information on qigong he also gives information on the qigong system or practice that he teaches. It is important to know which basic type of qigong he teaches – open system or closed system.
Zhineng Qigong e.g. is an open system.