It’s inevitable. Employees are going to start to resign and maybe in waves as the economy improves. While we may think we know why they are leaving, only asking those exiting will get you the information you are seeking. While forms and template questions are commonplace, consider a more freeform approach, designed to find out why they are leaving, perhaps by asking them what could have changed 6 months ago that would have ended their pursuit of a new role before it even started.
All companies regardless of size should have a formal Exit Interview conducted with employees that have resigned. The goal of this meeting is to better understand why this individual has chosen to leave your employment. The amount of valuable information that could be collected via such an exercise is astounding and highly valuable. You could learn of festering issues, company-wide perceptions of management, and even get a sense of what future resignations may coming down the pike. The effectiveness of these meetings heavily depend on who conducts them…so consider using a third party in order to secure the most complete feedback.