Your manager shouldn't be in your immediate family. In other words, don't get a parent or spouse to do the job of a professional. Management is a real job that requires real skills.
Parents screw things up. They believe the publicist-generated hype, are too close to the situation, and are often living their own dreams through their "client."
Worked with a 15-year-old maybe two years ago. She was a very nice, very attractive, and very talented singers. She was good and everybody who heard her demo wanted to help her. In fact, she was so good that a couple of major labels were interested. Everything looked bright for her.
But her father... That guy was a passive-agressive jerk who made it very difficult to get anything done. He was extremely high-maintenance and was constantly taking up valuable resources that would have been better used on his daughter and her career.
My time is too valuable to deal with idiots, so I stopped working with her.
A few months later, at SXSW, her name came up in a conversation. I was talking to an established music attorney who was interested in her, but had reservations because "her father is a real asshole."
Obviously, this could happen with somebody you are not related to, but it's not likely, especially if you're careful about selecting somebody to work with. Professionals in this business understand how to work with people and know how to do it in a way so that things get done.
You wouldn't get your relatives to play on your record, so why have them do something that is just as important?
This rule also applies to your spouse, by the way. Watch Spinal Tap and you'll see exactly what I'm talking about. While the movie is a joke, the situation when it happens in real life isn't nearly as funny.
