Speak to the back of the room. Loud and clear.
Give good eye contact with your audience. You don't have to look at them. Look through them.
Practice your speech so you know most or all of it by heart. Constantly looking or reading from your notes is a quick way to lose your audience.
Be confident. Speak as if what you are saying is the most important thing your audience will ever hear and that you believe everything you say and that they should believe everything you say.
Smile , be relaxed, introduce yourself, greet the audience, and at the end, thank them for their time for listening to your speech.
