Design is vague. I know. In this context, I’m referring to both system design and graphic design.
When I design anything, my top priorities are usability, accessibility, and beauty. With these principles in mind, I built a17t, my CSS library, and designed several other websites (including the one you’re on right now). I also do my best to apply these principles to software design and writing, but that’s harder to showcase.
(If you’re curious to see the evolution of this website, here are its incarnations: 2017, and 2019)
P.S.: In my (limited) experience, the principles I mentioned above almost always work together. A design with great usability will probably be accessible and beautiful, and vice versa. (That’s not to say that special effort isn’t sometimes required in some categories, especially accessibility.) As a bonus, I’ve found that the best design is often the simplest — so I try to avoid complexity wherever I can.