1. Have an elevator pitch
The first person to present last night is the CEO of a really interesting company trying to change the way business is done on a massive scale. He gave a great presentation, and told a really impactful story about the need for his business and his solution. I was completely sold, but the VCs all had concerns about his ability to present his idea to the market. In one person's words, "If I can't explain your business in 2 sentences, we have issues.
2. Have a revenue model
It seems simple, but it is critical to have a clear business model. There are often several viable revenue models for a particular business, and you need to explicitly explain how your business will make money.
3. Show graphs, not numbers
When you don't have hard numbers, don't expose yourself to needless criticism. This is especially true when presenting long term projections such as 5 year projected revenues and net income. Since these are rough projections, showing trends is enough, and putting numbers on the screen is just inviting for trouble. And if you're going to show numbers, say year 5 revenues will be $10,750,000 not $10,754,886.13.
4. Business model matters
Just as there are multiple possible revenue models for most business, there are also multiple possible business models. Make sure that the model you are proposing is the one that makes the most sense. For example, one group put together a really nice presentation for a product they are looking to sell B-to-C at first, followed by a phase 2 shift to B-to-B sales. During the discussions, there was criticism of this choice. Criticism could have been avoided with a more thorough explanation of the choice of the business model.
5. Don't make claims you can't back up
This was a big one. Don't claim you can manufacture a product at a cost that seems abnormably low. Don't claim your product will be the most successful iPhone app ever created just because it helps the presentation. It is clear to the audience that you're taking liberties with your presentation, and this seems to be a really easy way to qualify yourself out of consideration.