What is the best tip on hiring

Always hire the best people. Firms that save money by hiring people they can afford are headed to mediocrity. It is always better to hire one exceptional performer at a high salary than two average performers.
The 80/20 rule applies with hires as well, and should teach construction employers to look for a hire that will become one of their top 20% of employees who produce 80% of the construction employer's revenues. Most successful CEOs will say, "You can never over invest in your top people."