Dr.Pang said:
First, follow the natural laws of Qigong.
Do not overly pursue certain desirable phenomena during practice—such as special abilities or extraordinary skills—and avoid setting rigid expectations for yourself in advance.
If you fixate on these goals and constantly chase after them, you violate the principles of qigong. Problems that arise are not caused by diligent practice itself but by failing to follow the natural laws of qigong.
Second, when practicing from books, it's best to follow a single system or lineage rather than mixing methods from different sources. Combining techniques can easily lead to problems.
Without a teacher's guidance and prior experience, you may not understand the core principles or essential foundations of a particular method. What you adopt from one school might contradict another, creating complications.