Kurt Vonnegut at the San Diego State University website:
Find a subject you care about and which you in your heart feel others should care about. It is this genuine caring, and not your games with language, which will be the most compelling and seductive element in your style.
I am not urging you to write a novel, by the way — although I would not be sorry if you wrote one, provided you genuinely cared about something. A petition to the mayor about a pothole in front of your house or a love letter to the girl next door will do.
2. Do not ramble, though
I won’t ramble on about that.
3. Keep it simple
As for your use of language: Remember that two great masters of language, William Shakespeare and James Joyce, wrote sentences which were almost childlike when their subjects were most profound. “To be or not to be?” asks Shakespeare’s Hamlet. The longest word is three letters long. Joyce, when he was frisky, could put together a sentence as intricate and as glittering as a necklace for Cleopatra, but my favorite sentence in his short story “Eveline” is this one: “She was tired.” At that point in the story, no other words could break the heart of a reader as those three words do.
Simplicity of language is not only reputable, but perhaps even sacred. The Bible opens with a sentence well within the writing skills of a lively fourteen-year-old: “In the beginning God created the heaven and the earth.”