Can you manage them?
As a manager, you must get work done through others. So, once you've determined that a candidate is qualified for the position, find out if they will be manageable. Asking a candidate to describe the qualities of a good manager; to explain how their previous boss got the best out of them; to discuss how they handle constructive criticism; or to describe the worst manager they ever had will help you determine if you can successfully manage them.
Are they right for your company?
Gauging how a candidate will fit in with your corporate culture is extremely important. Make sure the candidate's goals and their dedication to reaching them dovetail well with your company's vision. For instance, if your company emphasizes a team environment, a candidate who prefers working solo may not be the best choice.
"Right" vs. "Perfect"
Ultimately, there are no assurances when hiring an employee. The "perfect" candidate may not exist, but the "right" one probably does. What constitutes the "right" hire? A person who is able to do the work, someone with team spirit and who is manageable, a professional who fits the corporate image and who is personally compatible with your company, and an emotionally mature adult with sound and rational judgment who will be a tremendous asset to your department and your company.
Hiring the right people for your company is one of your greatest challenges as a manager. With some extra hard work and a keen eye for the best candidates, you are sure to find your next great employee.