Command the room
One of the habits that holds speakers back is writing style. Sentences are too complicated, language is too formal, and there's too much information. Audiences get bored and confused.
Learn to write for listeners not readers. Deliver information in bites the audience can digest. Reflect real human thought and emotion with language that is direct and personal, while maintaining the depth of your ideas. Observe the natural rhythm and structure of spontaneous speech.
Great writing makes for great delivery.