As in a speech?
Make sure to have lots of eye contact (looking up once a minute isn't any good! try and memorise your speech so you can look up as much as possible)
Don't start off with something like "Good morning_____ the purpose of my speech is to_____" or "The dictionary defines _____ as _______"
Try to involve your audience by starting with a verb such as "Imagine a world with___". Ask rhetorical questions such as "Members of the audience, can I suggest here that perhaps ______?" or "Would you agree with me if i suggested that _____?".
Hope that helped