Persuading someone to part with his or her money in exchange for a stake in your startup is one of the most important things you can do to protect its future. Yet countless entrepreneurs sabotage themselves in the first five minutes of meeting a venture capitalist. Here's what not to do.

1. Fumble your elevator pitch.

The first question a VC wants you to answer is why your venture is going to make him a bundle of money. If you can't provide an irresistibly compelling answer in less than 90 seconds, don't even take the meeting. Doing this well means you must have practiced answering the following questions: What is the human pain that your startup seeks to relieve? Why will people pay for you to relieve that pain? How do you know your solution will work?

2. Be shy about past accomplishments.

The world of startups is like just about any other endeavor on the planet--it's hugely competitive. That means most people will lose and only a fraction will win big. If you want the VC to invest in your startup, you must convince her that you thrive in the race for success. If you can't demonstrate a track record of winning--whether in academics, sports, or other competitive endeavors--then the VC is not going to give you a shot.

3. Hire mediocre people.

If your venture has a mediocre startup team, the VC will quickly lose confidence in your judgment. He'll wish he could kick you out of his office and use the next 55 minutes for something more productive. If you are not comfortable hiring a great team and motivating it to perform, replace yourself with someone who is--before you meet with an investor.

4. Have a vague understanding of your financial needs.

If you're lucky, a potential VC will ask you how much capital you need. If you can't give him the right number, you will immediately lose his attention. The right answer is different for every startup. But if your startup needs, say, $10 million, you should be able to demonstrate the market is big enough to generate a return on such a big initial investment.

5. Skip the customer research.

If you haven't figured out who the buyers and influencers are for your product, you will leave the VC empty-handed. And you have to do more than just know who they are--you should have long conversations with at least 100 of them. Don't meet with investors if you don’t know the answers to questions like: Why does the problem your company is solving matter to the buyer? Who are your competitors? What criteria will the customers use to sort through these competitors? Why is your product going to come out on top? How long will it take to close a sale? What evidence will you need to give all the participants in the decision-making process to win them over?

Before you get into the room with a VC, make sure your pitch for capital is free of these fatal flaws. Otherwise, cancel the meeting.