As these gentlemen have stated.
Learn to express yourself in the
MOST professional manner possible, both oral and written. I (as well as others here) have briefed and lead discussions with Ambassadors, Secretaries (SECDEF, SECSTATE, multitudes of assistants and deputy assistants, Four Stars and below), and Congress; some of our work has been seen by the POTUS. I/we have been lucky to be a participant of high-level official exchanges between the USG and other nations (leaders of countries). You may too, IF YOU MAKE IT,
and you could be possibly the lowest ranking person in the room, but they will not care if you are professional, well behaved, knowledgeable, and can express yourself as such.
Effective writing
Public speaking
Leadership