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

You have to be decisive. Indecisiveness is a startup killer.

Move fast. Speed is one of your main advantages over large companies.

The thirteenth search engine- and without all the features of a web portal, most people thought that was pointless.

If you pivot, do it fully and with conviction. The worst thing is to try to do a bit of the old and the new-it's hard to kill your babies.

One of the great and terrible things about starting a start up is that you get no credit for trying.

In YC's case, the number one cause of early death for startups is cofounder blowups.