How do you build a great team for a successful startup?

I worked as an engineer at both Palantir and Facebook.  There are a lot of differences between the two engineering organizations, but both companies have built engineering organizations that are highly productive and supportive of the success of the business.  Here are the main features that I think are shared by these companies:

1) An interview process for engineers that requires all candidates to be proficient in answering rigorous algorithmic questions.  No other metrics are required to be hired.  Instead interviewers summarize their overall estimate of how likely a candidate is to be a "great engineer".  These estimates include factors such as depth and breadth of knowledge about various topics related to the job or engineering in general, soft skills, track record of producing measurable results, evidence that the candidate enjoys coding enough to do it in their spare time for fun, etc.  Years of experience and credentials are generally not determining factors when making hiring decisions.

2) Individual engineers are viewed as an essential source of ideas and feedback that will have a material impact on the overall direction and strategy of the company.

3) A culture in which individual engineers are encouraged and also organically motivated to be evangelists for the business in general.