In this recent post from PHPMaster.com Aaron Saray gives a few helpful hints (and reasons to speak) for the aspiring presenters out there wanting to give their first talk at a PHP (or any technology-related) conference.
Your heart begins to race. Suddenly, it's stifling hot in here. Your palms begin to sweat and your knees are threatening to give up and flee to a vacation in Cancun without you. The dull rhythmic thump-thump in your ears heightens to a frenzied jack-hammer. You can't remember a time when your mouth has been this dry. It's time to begin - and your voice cracks. It's public speaking time and you're the next one up. In this article I'll cover the basics of why presenting PHP is important, who can present about PHP related topics and what you can do to make your presentation stand out.
He starts off by answering the "why" question - why even give a presentation at a conference or local user group? His answer has a few parts and involves things like giving back to the community and being considered an expert in the field. He follows this with a few ways to help your talk stand out - include code samples, give live demos and be entertaining.