Adjust your volume to fit the situation. Speak louder if you’re giving a speech or proposing a bold idea to the CEO. Speak softly in an emotionally charged setting.
Toss the garbage. Crutches in your speech undermine your authority. Repeating “if you will,” “perhaps” or “you know” adds nothing. Only say “I don’t know” if you truly don’t know the answer to something, not to indicate uncertainty, as in, “I like that approach. It’s so ambitious, I don’t know ...”
Control yourself. Limit your movements so that they enhance what you say and help listeners visualize your points. Don’t wave your arms, fiddle with rubber bands, jiggle your leg or rub your cheeks, eyes or scalp. Such antics make you seem weary or strange.