Speak only if it improves upon the silence.
Before saying anything, consider this: Is it kind? Is it necessary? Is it true?
I'm paraphrasing, because I can't remember the exact quotes, but the first is attributed to Gandhi, the second to the first Buddha.
Is it necessary to tell a person they they are on the "Do Not Rehire" list? Is it necessary to discuss how much money you make? Is it necessary to talk about bonuses that you choose to give one shift over another?
When we communicate, it should be with the intent to help and inform. The paragraph above lists things that do not need to be communicated. While they may be informative, they're certainly not helpful.
Here's a couple more words to live by:
"Do unto others as you would have them do unto you." Jesus
"Harm none." from the Wiccan Rede.
Actually, that last one covers it all.