Often the owners of $15 million-plus homes don’t want everyone to know they’re selling, so it’s more who you know than what you do.

"I have clients say 'I don’t want anyone to know the house is for sale,'" explained Sotheby’s International Realty agent Arthur Sharif. "I’m forbidden to market the home, per se. That’s where it becomes important you have connections, that you know who to reach. And so that people know you, so they know to pick up a phone when they have a client who is looking for a home in a certain area."

To read Sharif's other tips for selling a multi-million dollar home, click here for Zillow's (Z) blog.