It really is true that you become an average of the people you spend the most time with.

At YC we have this public phrase, and it's relentlessly resourceful.

Before 20 or 25 employees, most companies are structured with everyone reporting to the founder. It's totally flat.

In general, it's best if you're building something that you yourself need.

It's difficult to get large groups of people, to the extreme levels of focus and productivity that you need, for a startup to be successful.

Companies that I've been very involved with, that have had a very bad first hire in the first 3 or so employees never recover from it.

If someone is choosing between joining McKinsey or your startup it's very unlikely they're going to work out at the startup.