One of the things no one really warns you about in high school, when you start considering a career in science or engineering, is how frequently you'll have to present. Even if you do get warned, unless you're involved in speech in debate club, no one teaches you presentation skills, right? Wrong. Some of the most important things I've learned about how to give a good presentation I learned in marching band.
1) How to stand attentively, yet relaxed ("at ease"): Standing up straight conveys confidence to your audience, but most people tense up when they think they're standing straight. I also learned the fine art of not locking my knees... seriously, fainting doesn't look good.
2) How to breathe properly: Yes, you aren't fainting from a lack of oxygen, and you've been breathing your entire life (hopefully). That doesn't mean your doing it in the most effective way possible. When you take a deep breath, you stomach should move, rather than your shoulders and chest lifting. Taking a controlled breath can slow down your heart rate and help you calm down, if you're like me, and race through presentations.
3) Speaking loudly without yelling: How many presentations have you been in where you can barely hear the speaker in the second row of a small room? I'm willing to bet at least a few. Volume in speaking doesn't come from your throat, it comes from the diaphragm. Using air (which you'll have more of if you take better breaths) can support your voice, making you sounds less nervous. Most women with high-pitch voices also find that this helps pitch their voice down a bit.
4) The important of pauses:First, go watch this. Don't worry, I'll wait.
The pauses create interest and drama, making the listener more attentive to what comes next. By pausing, you can emphasize the following statement. This a wonderful time to take a good breath.
So you weren't in marching band? Finding a band geek isn't hard: just mention John Phillips Sousa loudly, and wait for them to come out of the woodwork (warning: there are very few moderate opinions on Sousa...) But really, my point is that skills you thought were unrelated to what you do can come in handy.