" People you’re contacting to create a new relationship need to see or hear your name in at least three modes of communication—by, say, an e-mail, a phone call, and a face-to-face encounter—before there is substantive recognition. • Once you have gained some early recognition, you need to nurture a developing relationship with a phone call or e-mail at least once a month. • If you want to transform a contact into a friend, you need a minimum of two face-to-face meetings out of the office. • Maintaining a secondary relationship requires two to three pings a year. • Social media pings (status updates, retweets, comments, etc.) are terrific for ongoing relationship maintenance, especially for the fringe of your network, but they don’t replace the need for one-to-one pinging with the people in your highest-priority network, those people connected to your current goals. "

― Keith Ferrazzi , Never Eat Alone: And Other Secrets to Success, One Relationship at a Time