There are no hard rules when it comes to art. However, there are principles that form the basic building blocks for all the visual arts and principles that guide an artist when they are composing a piece. These are often called "principles of art" and "principles of design." These vary only slightly from person to person.
My question to you is two fold: Do comics have basic principles? If they do, what (in your opinion) are they?
Most comic books that teach you to draw only focus on one style, rather than teaching you how to create comics in your own style. I hope to someday make a course on drawing comics that looks past styles and teaches core principles that anybody drawing comics would find useful.