Concentrate on the message - not the medium
Focus your attention away from your own anxieties and concentrate on your message and you audience.
For any nervousness or problem - the audience probably never noticed it.
Realize that people want you to succeed
Audiences want you to be interesting, stimulating, informative and entertaining. They don't want you fail.
Visualize yourself giving your speech
Imagine yourself speaking, your voice loud, clear and confident. Visualize the audience clapping - it will boost your confidence.
Ease tension by doing exercises. Transform nervous energy into enthusiasm.
Know the room
Arrive early, walk around the speaking area and practice using the microphone and any visual aids.
Know the audience.
Greet some of the audience member as they arrive. It's easier to speak to a group of friends than to strangers.
Practice. Practice. Practice!
Rehearse out loud with all equipment you plan on using. Revise as necessary
Know your material
Pick a topic you intersted in. Know more about it than you include in your speech.