Some days back I built up this list as a sort of a guideline for myself and also something I could tell my students when they start my class. These are the things I base my teaching:
The knowledge of the craft of making comics and the tradition of. Also the history of the art form. Things don't just appear from nowhere and a student of comics should be interested and aware of the rich history of the art form. This includes the knowledge of how comics have been made and why certain material has been favored.
Material is one of the most important factors in making any art. It can only be learned by using a material. The material of computer software is unclear to me and, to my experience, to my students. In a material world the feel of a pen on paper is essential in order to learn a material.
Most of my assignments require observation from the students. Observation is essential in writing and making comics. It's essential at all stages of the work. What makes a character act as he/she does? Be observant.
And as I say to my students: you have to have something to say. You don't have to know what it is, but you have to have it.