You missed Sama's awesome post on "How to Get Into Y Combinator" (which is sadly now private) Here are some good sections:<p>For most startups at this stage, the best predictor of success is the founders. So, the most important parts of the application for me are the questions about the founders' backgrounds and the most impressive things they've done. We're looking for evidence that the founders are smart, effective, and determined. If you can't go through your application and point to evidence for all three, that's bad. Don't be shy about telling us why you're good, but don't write a bunch of meaningless marketing speak either.<p>The first question I usually ask is something like "so, why this idea?" I'm happy when founders say things like "we wanted this for ourselves" or "we understand this space better than anyone else because of Y". We ask about parts of the business we have concerns about, like market size, competitive differentiation, growth plans, business model, etc. In particular, I'm interested in seeing how founders react to new information, and if they're flexible while still standing their ground on things they believe in. If I've already thought of everything a founder has to say about his/her company, that's bad.<p>It's important to remember that most investors are optimists by default. We want to believe that we've just found the next Facebook.