Keep speeches and presentations short. Ideally, no more than 25 minutes. Long and ongoing presentations turn into rambles. Audiences turn off and begin clock watching.
Choose words carefully. They need to fit the audience profile. Presenters should avoid talking up and talking down to audience groups. This will happen if the audience type or group is researched and that is a hallmark of respect for listeners.
When speaking, make whole sentences impactive. Don’t fade away toward the end of sentences and don’t clip statements in a way that reduces their impact and meaning.