Did they seem earnest? Were they determined? Were they flexible-minded?  And most importantly, what was the relationship between the cofounders like?

From the beginning I was careful about only funding earnest people. Back then, I never envisioned the people we funded growing into a community of thousands of YC alumni, but I always tried to create an asshole-free culture. If I could tell someone was a conceited asshole, we didn’t fund them.

What YC needed was deeply technical people to understand the potential of an idea, and someone like me to understand the founders' characters and the relationship between them.

One other thing Paul and I had in common was that we weren't driven by money. We were interested in startups and we wanted to help people start more of them. This was the basis for everything we did at YC. It was what allowed us to do something as weird as YC in the first place.

One thing we've learned from Y Combinator is that the most successful startups tend to grow organically out of the founders' lives.

if you want to start a startup, I recommend you try asking yourself what's distinctive about you. What unique combination of abilities and interests do you have?  And don't edit your answers, because as my example shows, the most unlikely ingredients could be the key to the recipe.

the most successful startups do tend to be weird. They're usually such outliers that the idea sounds preposterous at first. To everyone except the founders, because the company has grown out of their experiences.

1. There is no one mold for a successful founder.  Just because you might only see a certain type in the news, that doesn’t mean you need to turn yourself into that.

2. Do what you’re genuinely interested in and try to play to your natural strengths. A startup is so much work that you'll give up if you're not genuinely interested in it.

3. Don’t pay attention to the mainstream’s opinion of what you're doing—whether it’s your skills, your idea or whatever.  Unless they’re your users, their opinion does not matter. (Pay a lot of attention to your users' opinions though!)

4. Find a cofounder with complementary skills, but the same moral compass as you.

5. Focus on making something people want. Everything follows from that. In 2005, people needed a way to get a small amount of funding easily.

9. Be intrepid. There's room for lots of different kinds of people to be startup founders, but you do need a certain amount of boldness—to work on ideas that most people would consider stupid, and to keep going when you're ridiculed or ignored.

You are a jigsaw puzzle piece of a certain shape. You could change your shape to fit an existing hole in the world. That was the traditional plan. But there's another way that can often be better for you and for the world: to grow a new puzzle around you.