SAN FRANCISCO — Many real estate agents start out keeping track of their clients using a simple spreadsheet. But if they want to step up their game, they should use a customer relationship management system, according to panelists at the “Client Tracking and Nurturing — CRM Tools for Success” session at Inman Connect today. “If your spreadsheet is working for you today, that’s great. It will not work for you tomorrow,” Kendyl Young, founder and owner of Los Angeles boutique brokerage Diggs, told conference attendees. “We are in a space in the industry where amateur hour is over,” she added. “We’re past the place where four transactions a year” is enough to have a successful career, she said. A CRM that gets a client “from contact to contract to aftercare to repeat and re…