I consider myself an inventor first and an entrepreneur second. In real life, my hero is Thomas Edison. He was a great inventor, but also an outstanding entrepreneur who was able to sell his inventions to the masses. He didn't just develop the light bulb; he invented the entire electric grid and power distribution system.
After building most of Mint.com's prototype by myself, I talked to anyone and everyone I knew about Mint. It's counter-intuitive, because you might fear someone will steal your idea, but it's the only way to make connections, be sure you're on the right track, and provide a solution for an audience broader than yourself.
One of my top tips for aspiring entrepreneurs: Tell everyone you know about your idea. This runs contrary to the instinct that most people have, because they're afraid someone is going to 'steal my ideal.' Ideas alone are worth very little; it's in the execution and market feedback that companies are made.
I actually don't invest in anything that is social, mobile, deals or ad networks simply because those are areas where there are so many players and so many other smart people in the space, I feel like I don't have a competitive advantage. So I tend to go after things that are e-commerce, like healthcare.
Mint's business model became, 'We'll go for free, and then we'll find these savings opportunities for you.' You know, better interest rate on your credit cards, when should you consolidate your student loans, when does it mathematically make sense to refinance your mortgage, and Mint figures all that stuff out for you.
When I was 8 or 9, I started using bulletin board systems, which was the precursor to the Internet, where you'd dial into... a shared system and shared computers. I've had an email address since the late '80s, when I was 8 or 9 years old, and then I got on the Internet in '93 when it was first starting out.