You have to be decisive. Indecisiveness is a startup killer.
At YC we have this public phrase, and it's relentlessly resourceful.
I think as a rough estimate, you should aim to give about 10% of the company to the first 10 employees.
Stay focused and don't try to do too many things at once. Care about execution quality.
Before 20 or 25 employees, most companies are structured with everyone reporting to the founder. It's totally flat.
You need to have a culture where people have very high quality standards in everything the company does, but still move quickly.