Most great companies in tech have been built by personal referrals for the first...at least 100 employees and often many more.

You also want to fire people who a) create office politics, and b) who are persistently negative.

Later, you should learn to hire fast and scale up the company, but in the early days the goal should be not to hire. Not to hire.

You need conviction in your own beliefs, and the willingness to ignore others naysaying.

A small communication breakdown is enough for everyone to be working on slightly different things. And then you loose focus.

No growth hack, brilliant marketing idea, or sales team can save you long term if you don't have a sufficiently good product.

So always keep momentum, it's this prime directive for managing a startup.