Opinions for Writing Good CSS
Agree with about most of these. Especially the part about formulating a complete understanding of a responsive layout before trying to code it. Would add that coding it is a valid way of building that understanding. Just gotta be a little bit present in the creative process, notice when it's time to cut your losses on that first draft, and try again from scratch.
CSS is a flexible language that, in my opinion, requires opinions to be written well and consistently. Here are some of my opinions for writing good CSS.
www.andrewwalpole.com/blog/opinions-for-writing-good-css/