Hello.
1. Schizophrenic people should not practice Qigong. Energy follows consciousness. If your mind is scattered and imbalanced, your Qi circulation will be too. You should instead learn basic relaxation/stress-relief skills, and you will know when you are ready to take your simple meditation into deeper practices like Qigong exercises.
2. Qigong deviation is rare and unlikely, and you should not be afraid to practice qigong if you are healthy and have a strong foundation of awareness of reality. If you are a deluded person who has mental problems, chemical imbalances, or anxiety, see #1.
3. Herbs and drugs should be avoided unless required temporarily for a serious condition or injury. Qigong practitioners strive to regain the full potential of their connection to nature and the natural way of being. This means we must slow down to a pace of living that is more like it was in ancient times, avoid excessive stimulation from electronics such as TV/computers, eat a basic diet of natural foods without chemicals/preservatives/pesticides, and practice simple relaxing meditation every day to support your Qigong exercises. If you do not live naturally in this way, you will encounter difficulty in your practice because your body and mind will be in an unnatural state.
Go outside and breathe slowly, quietly, deeply...
Enjoy your practice.