Never put too much trust in friends, learn how to use enemies: Be wary of friends — they will betray you more quickly, for they are easily aroused to envy. They also become spoiled and tyrannical. But hire a former enemy and he will be more loyal friend, because he has more to prove. In fact, you may have more to fear from friends than enemies. If you have no enemies, find a way to make them.
This is certainly one rule that I can honestly say I have lived and learned from. Going forward, my rule will be to never hire friends or family.