You never want to be in a place where an employee has vested 3 out of the 4 years of stock and they start thinking about leaving.

The natural state of a start-up is to die; most start-ups require multiple miracles in their early days to escape this fate.

Be suspicious of any work that is not building product or getting customers. It's easy to get sucked into an infrastructure rewrite death spiral.

We've seen a lot of data at YC now, and the most successful companies and the ones where the investors do the best... end up giving a lot of stock out to employees- year after year after year.

The other piece besides focus for execution is intensity. Startups only work at a fairly intense level.

You want an idea that not many other people are working on, and it's okay if it doesn't sound big at first.

Remember that the idea will expand, and become more ambitious as you go.