Share results (financial and key metrics) with the company every month.
Stay focused and don't try to do too many things at once. Care about execution quality.
A single mediocre hire in the first five will often in fact kill a startup.
Experience matters for some roles and not others.
Whatever the founder cares about, whatever the founders think are the key goals, that's going to be what the whole company focusses on.
Growth solves (nearly) all problems