Whether you're speaking to a small group in a board or committee meeting or an audience of over one thousand at a trade show, make your presentation intimate. If you use a microphone, try to use a small wireless mike attached to your lapel or tie so that you can move around. Engage particular people in the audience for short periods by moving toward them and establishing eye contact. Don't read your speech. Nothing will cause the premature death of your audience faster than a speech that you read.
Eye contact is lost and gone forever.
Unless you are one of a small fraction of one percent of people on this earth, you will slip into a monotone at the second word. Your voice will not project. You will most likely mispronounce words. In general, you will screw up the whole speech. A speech must sound sponaneous, even when it's prepared.