Knowing when to say "no" can keep your company from making a mistake that will jeopardize its growth potential. Here are four lessons that can help finance execs keep their companies on track. No. 1: Don't chase after opportunities that will distract you from your core market. "When you turn your attention to growth, one of the hardest things is to remain committed to what you've determined you're not going to do," CDW Chief Financial Officer Ann Ziegler says.