Plainness

Now that doesn't mean that plainness is the only good style, or that you should become a slave to spare, unadorned writing. Formality and ornateness have their place, and incompetent hands complexity can carry us on a dizzying, breathtaking journey. But most students, most of the time, should strive to be sensibly simple, to develop a baseline style of short words, active verbs, and relatively simple sentences conveying clear actions or identities. It's faster. It makes arguments easier to follow. It increases the chances a busy reader will bother to pay attention, and it lets you focus more attention on your moments of rhetorical flourish, which I do not advise abandoning altogether.