Do and donts in communication

Communication,

Let us look at issues in your own post or question?

First was not a full sentence.

You did not give any guidelines as to what type of communication, verbal, non verbal, if non verbal what type.

You did not state, if this is homework, what grade level, or what text book, since if homework, what one author believes or teaches as the "truth" will be taught differently by another school or text book.

So mail do or even don't,

You have to make clear what you are trying to say or ask