First keep peace with yourself, then you can also bring peace to others.

Calm you have not found in yourself is difficult to hand to anybody else. When you are at war internally, whatever you offer arrives carrying the static of that fight. The order matters here, not because you must be finished before you are allowed to help, but because unsettled people tend to spread their unsettlement without meaning to.

Notice what you are carrying into a hard conversation before it starts. A few minutes of quiet, or simply naming to yourself what is actually bothering you, changes the tone of everything that follows.