Know a something about a lot of things. Have some knowledge in your head on as many subjects as possible. That way whenever something is overheard or read instead of having to say ” I have no knowledge about that” or even worse ” I haven’t a clue about what you are talking about”, you will be able to say “that is interesting, now I know more about that subject” or you will be knowledgeable enough to be included in the conversation as an equal.
Learning never stops. Don’t limit yourself.