Pitching can be a very intimidating experience, especially when founders believe that it will make or break their startup. I usually like to have meetings where I feel like I'm indifferent to the outcome, even if the outcome is incredibly important. But an attitude that it doesn't matter helps me act more naturally. And as Jim Rohn teaches: "Don't bring your need to the marketplace, bring your skill."
Sounding needy is off-putting. People - especially investors and customers - don't want to feel like they're doing businesses a favor. They want to feel like they're getting way more value than what they're spending.
If you sound needy, the dynamic is no longer investment but charity, and it's hard for investors to overlook this impression and focus on the actual pitch.
Therefore, try to be as natural and composed as you can. Express confidence not desperation.
It's also important to imagine and address your ideal audience. There are 3 qualities your ideal audience/audience member should possess when preparing a pitch:
1- They're an investor: This depends on the kind of pitch you're preparing, but if you're thinking about your startup as a business, it's important for you to address an investor. A friend, customer, another startup founder can distract you from building a business case for your business. You may end up talking about the problem you're solving or how great your product is without making a persuasive argument on how you'll develop a successful business.
In fact, I would recommend preparing a pitch early on in the startup to think more clearly about what would make your startup a viable business.
2- They're supportive: Don't assume your audience is looking to find faults in your presentation. They're on your side. They want to see you succeed. If this is not the case, then you might not want to deal with such investors in the first place.
3- They're smart: Don't insult their intelligence by glossing over weak points in your presentation. Respect their intelligence and admit what the weaknesses are and what you intend to do about them. You may even want to point out what you need help with (and what kind of support you're looking for from your investors. Remember point #2: They're on your side).
These 3 points help you develop clarity of purpose, remove any emotional apprehensions, and help you craft an intellectually persuasive argument.
If you're a startup founder or investor, I'd love to know what you look for in a pitch and what you've found useful in giving a pitch.