You don't have to be best friends [with your co-workers], but being polite, respectful, engaging, and on the ball is critical to your ongoing success,” says Lori Scherwin, founder of the New York City–based career coaching firm Strategize That. “Your demeanor and relationships often count at least as much, if not more at times, than the work product itself. If people enjoy working with you, you are more likely to get additional opportunities.”