Who are you? How do you expect me to trust you? I know you do, because you're trying to sell me something. You're a startup; you put together a cool tool, working with your friends in a garage. You're ready to hit the market. No-one knows you.
When you don't have past achievements to speak for you, then all you have is transparency. Blog, tweet, share. Write about your ups and downs, explain your philosophy, speak of what you learn while working. It's not likely to get you a seven-figure order, but it will build trust among your prospective customers and at some point some exec with a budget surplus will say “o hell, let's check these guys out.”