It's important to have principles.

When I was first learning about Jazz harmony, my high school music theory teacher assigned us each a chart to copy down by hand, note for note. Once you had a chart copied, you were to listen to the original recording and transcribe each solo, note for note. In this way, we learned how to bring together musical elements and improvise over them. Learning the principles of design is not too different. To understand the process that brings an idea into form, you need to look at each component carefully and draw what you see.