The ability to say the right thing at the right time is a mark of a true master. I recommend working on listening skills and the conciseness of your speech if you want to develop this ability.
Successful communicators are paying attention to how people perceive their messages, understand who they are speaking to, and establish a rapport. It is important to pay attention to intonation and voice.
Often, when we talk to others, we do not have the patience to listen. We hear a few words and very quickly we start anticipating what the other person will say. We even try to finish their sentences which are not very helpful, particularly for the person who is talking. Do not do that!
In order t say the right thing at the right time we should listen, pause, think and reply. This will allow us to create a better response and modulate our voice accordingly.
2. It is better to speak less and answer only those questions that are being asked of you. Make your answers clear and stress the key messages. You can learn about it with the apps Get Rid of your Accent and Fluent English Speech.
I have noticed, that some people try to talk a lot, and make silly jokes in order to feel comfortable. When people try to prove themselves they often speak fast and try to say all they know in a short period of time. In my opinion, it is better to not say much, instead, listen and smile more.
It would be wise to avoid negative and sensitive topics, such as politics, religion and money to avert conflicts and offending others.
Jacqueline Kennedy once said: "I sometimes have regretted what I said, but I have never regretted my silence."