Start immediately. Begin practicing as soon as you find out that you have a presentation due. Practice out loud, every day. Practice in front of a mirror to make sure that you are looking up and not reading. Do it again and again and again.
If you have to write it yourself, don’t use a translator. Rather, ask your teacher if you can drop it off one day for a teacher’s review. Say that you wouldn’t want to memorize incorrect sentences. Ask how to pronounce a few words you are stuck on.
Don’t use words your audience doesn’t already know. (Unless there’s a requirement to use words that your audience doesn’t already know–which is rare.) New words produce blank stares. Blank stares will throw you off your script. If you’re the author of your presentation and you need to use a new word or two, introduce those new words before you begin. Put them on the board. Explain them. Then begin.
If you’re not the author, give credit to the author before you begin. Perhaps you’re reciting a poem or part of a speech. Give the audience a little background. Is this a revolutionary call to arms? When and where? Is this a falling in love poem or a break up poem?
Have emotion. Your voice and your face should match your words. Emotion shows that you “understand.”
Mumbling is not an emotion. Mumbling in front of a crowd conveys that fear of your audience is your strongest emotion. It makes your audience uncomfortable and your teacher wonder if you’ve practiced. If you find yourself mumbling while practicing, stop. You haven’t made the emotional connection you need. Dig deep and find how your words should make you feel. Practice.
Practice with props. Use props. Don’t ask if you must have props. Surprise your teacher. Make sure your props relate, they’re appropriate, and that they’re large enough to be seen clearly from the back of the room.
Project your voice for all to hear. Volume is your friend.