Constantly having to schedule and reschedule appointments makes for one messy calendar. The solution: Write tentative dates on one-inch Post-it notes. That way, if your notoriously flighty friend needs to switch tennis days (again), you can simply move the note instead of penciling and repenciling, says organization expert Stephanie Winston, whose latest book, Organized for Success (Crown Business, $15, www.amazon.com), offers clever, time-saving tips from busy senior executives and CEOs.