"Your success as a presenter will be judged by how you project your passion for your topic, your compassion for the audience and your over-all enthusiasm."
George Stewart, Quintilain Executive Communication
You are usually the most nervous during the first few minutes of a presentation.
Use an attention grabber: Start by grabbing the audience's attention, rather than the traditional "Good afternoon. My name izzzzzzzz". Stand up, look at the audience for a pause, and then hit them with the grabber. For example grabbers see:
You got my Attention! Attention Grabbers for Presentations (14 KB)
Memorize the first 2 minutes: Go ahead and memorize the first 2 minutes BUT ONLY THAT! You don't want to sound scripted.
Especially at the beginning of the presentation, look for at least one ally in the audience-someone who looks open and interested in you and your ideas. Looking at audience members with closed or negative body language too early may lead to increased worry and negative thoughts. It is alright to avoid direct eye contact with hostile looking audience members but you should make an effort at least gloss over them with your eyes so you appear assertive and confident.
All people love a good story so engage your audience by telling them Your Story (i.e. for research this would be your methods and results). Adding a human element with direct, 1st person speech gives your talk a friendly, personal tone rather than a stilted, text-book one, e.g. "I did this and then I did that, but that didn't work so I did something else".