When we were finishing our accelerator program there was a huge emphasis placed upon the pitch and we even engaged an absolutely stellar pitch coach, Andi O'Conor. We spent almost 2 weeks practicing, refining, practicing, iterating, practicing, and practicing. This was the net result of that practice.
Nothing can replace the grind of working through your pitch over and over again, but there are some principles that are easy to implement and can dramatically improve your credibility. I'm going to tell you exactly what to do, and then explain why I think it works so well.
1) Ready... SET... Go
What to do: Set before you speak. When you take your place, set your feet and pause for a beat or two before beginning your pitch. When you finish your pitch say "Thank you" and pause again for a beat or two before exiting.
Why: Your pitch should start off with a hook that grabs the attention of everyone listening. When you're taking the stage people use that opportunity to quickly chat about the last company, check their phones, scratch their ears, or whatever else. If you launch right into your pitch they might still be tying off their conversation and miss one of the most important parts of your speech. If you stand and pause for one second, everyone in the audience will finish up what they were doing and prepare themselves to hear you and then you can really sink the hook.
This also ties in the psychology that if you have something important to say, you will wait for people to be quiet before you say it. It conveys confidence and credibility if you can wait just a moment or two before you begin. Did anyone else have the experience in school where a teacher would say "I'll wait for everyone to be quiet so we can begin"? It's that kind of authority that you are conveying by pausing for just a moment or two.
2) Grinning is winning
What to do: Wear a small smile when taking and leaving the stage
Why: Again it's all about conveying confidence and credibility. If you're dreading the pitch and are worried about the tough questions you might be asked, those emotions will shine through on your face. Just by smiling you convey that you are feeling good about your product and your pitch.
Additionally it has been demonstrated that smiling makes you happy. Wearing a smile as you enter and exit the stage can actually make you enjoy pitching more. Never forget, you can hear when a person is speaking with a smile on their face.
3) All about Face
What to do: Always face your audience
Why: It's tempting to turn around to reference your deck, but even with a mic you lose a lot of communication. Keep in mind that people are there to hear you tell your story about the company. Your deck is just a colorful illustration of the narrative that you're weaving. You have to carry the narrative and be confident that you can deliver the message clearly. Turning your back is distracting and draws attention away from your message. You can cheat 15-20 degrees each way if you need to, but you should always have your face towards the audience.
Notable exception just because it's an amazing example of public speaking.
4) KISS your Deck
What to do: Keep It Simple Stupid. Remove any large blocks of text and stick to simple graphical representations of what you're trying to convey.
Why: You are, and should be, the center of attention. Any time you have large blocks of text on a slide your audience is going to try to read it. What's the likelihood that they can read your important text and listen to the words you're saying at the same time? Probably relatively low. If the text contains important information, include it in your pitch. If the text is not important, then remove it altogether.
When your slide comes up the audience should take a look at your slide, and then their attention should jump right back to you. The more complicated and involved your slides are, the longer the audience is distracted and the more they will miss. Less is more!
5) Stand tall, you're a champion
What to do: Stand up straight and plant your feet. Your feet shouldn't move almost at all while you're pitching. Don't lock your knees, but make sure you're standing up straight, not leaning one way or another.
Why: It's called body language because your body is telling it's own story about you while you are busy telling your story to the audience. If you're leaning one way or another it's like looking at a bridge that's about to collapse. You're not making anyone feel safe. Stand up as tall as you can and occupy and own your space like the champion you are.
Moving your feet about conveys nervous energy, which begs the question, "What are they nervous about?" so leave them in the same position from your introductory set, to your conclusion set. Feel free to gesture and be open with your body, but don't move below the knees.
Here is a great example of public speaking and a great explanation about the connection between body and mind. Very interesting, 20 minutes that are well worth it.
I'm sure there are a million exceptions to the basic rules I've outlined above. Certainly there are many ways to deliver an outstanding public speaking performance, but as a beginners guide this is a good place to start. When in doubt, ask yourself, "What would a really confident person be doing?" and try to emulate that. If your pitch isn't amazing, take the time to practice. It's a skill to be honed like any other. Good luck and let me know if this was helpful!