Listen carefully to applicant's responses and demonstrate that you have listened by taking notes and by asking for more specific information or examples when the applicant speaks in general terms. Never accept an incomplete answer. Don't get sidetracked. Set a starting date that doesn't allow the new employee to shop around or find a better offer. The longer the time delay, the greater the risk of losing a prospective employee.
Surveys show that the first person interviewed is often the last one hired.
Even if that person has the best qualifications, a quirk of human nature doesn't allow us to pick the first person we interview. Try to counter this tendency.