About 4 years back, I was literally petrified with the very idea of public speaking. Honestly, it took a lot for me to get over it. Now, my 2 cents worth of advice to you will be:
1. Bring passion to your speech. You are selling an idea, be passionate about it.
2. Respect the punctuation. Need I say more?!
3. Practice and put emphasis on the words or points you think are most important. Pause before and after a crucial idea, let it sink in.
4. Interact with your audience. Once you have delivered your deal maker point, engage with your audience and ask them questions. Keep it simple yet engaging so you get multiple response.
5. Once you are able to imagine that your presentation is nothing but you literally selling people a product (your idea in this case), you will understand the need for passion more than anything else.
In case you wish to discuss further, feel free to get in touch.