There are some suttas in the Pali Canon which have useful things to say about right speech. Here’s an overall guiding principle:
“It is spoken at the right time. It is spoken in truth. It is spoken affectionately. It is spoken beneficially. It is spoken with a mind of good will.” — Anguttara Nikaya 5.198
Here’s an except that helps us consider what is worth saying. It’s based on considering three things: is what you are going to say TRUE, is it BENEFICIAL, and is it WELCOME?
And then there’s the TIMING:
“Such speech as the Tathagata knows to be untrue, incorrect, and unbeneficial, and which is also unwelcome and disagreeable to others: such speech the Tathagata does not utter.
Such speech as the Tathagata knows to be true and correct but unbeneficial, and which is also unwelcome and disagreeable to others: such speech the Tathagata does not utter.
Such speech as the Tathagata knows to be true, correct and beneficial, but which is unwelcome and disagreeable to others: the Tathagata knows the time to use such speech.
Such speech as the Tathagata knows to be untrue, incorrect, and unbeneficial, but which is welcome and agreeable to others: such speech the Tathagata does not utter.
Such speech as the Tathagata knows to be true and correct but unbeneficial, and which is welcome and agreeable to others: such speech the Tathagata does not utter.
Such speech as the Tathagata knows to be true, correct and beneficial, and which is welcome and agreeable to others: the Tathagata knows the time to use such speech.
Why is that? Because the Tathagata has compassion for sentient beings.” — Majjhima Nikaya 58
[With thanks to Claralynn Nunamaker]
wannabe poet 