Teamwork is the foundation of success. The three universal questions that an individual asks of his coach, player, employee, employer are: Can I trust you? Are you committed to excellence? And, do you care about me?
The answers to these questions will determine your success or failure. 1) Can people trust me to do what's right? 2) Am I committed to doing my best? 3) Do I care about other people and show it? If the answers to these questions are yes, there is no way you can fail.
I'd say handling people is the most important thing you can do as a coach. I've found every time I've gotten into trouble with a player, it's because I wasn't talking to him enough.