Odds of Hanging On
It's a tough business. You might make someone's career, and then they drop you for someone more established. Your entire future might hinge on whether or not your few biggest clients stick by your side when the going gets good. So you may want to try to make them like you on top of merely being good at what you do. A little loyalty goes a long way.
That's important to note—not only are you seeking out the worthiest talent to spend your time managing, but you have to keep your clients satisfied so they don't give up on you, either. This relationship is a two-way street—you only have time for so many actors, so if someone isn't cutting it, you're going to have to cut them.
By the same token, you're only as good as you're making your client feel. And if they're not feeling very good, it's sayonara.