Carefully study the resume of the candidate and the presence (and the possibility to provide) - examples of his work. Think about what information indicates in his favor, and what - is questionable. Think that would like to understand the basis of this, specify questions.
If you want to add questions that shed light on the professional competence of the applicant (for example, as one will get out of this or that a given work situation).
Please rate your feelings from the previous dialogue with the candidate (by telephone, e-mails). This could give ground for further questions.
At the time of the candidate's visit to your office briefly tell him about the company offered the position, responsibilities. Better it does not reveal all the cards, and give the applicant cause for additional questions that can serve as an additional test: he will use the opportunity to ask them or not.
Set the prepared questions, listen carefully to their answers, fix the most significant provisions of the answers.
In turn, give the applicant an opportunity to ask questions and inform yourself further on what he sees fit.
At the end of the conversation, proceed on the situation. If you are interested in a candidate, you can discuss with him the possibility to get to work and further execution of relations. Or announce that the final decisions are not you, and agree on further cooperation.
Direct refusal candidate is usually not practiced, although often perceived as a promise to get in touch with the decision in favor of the candidate. Therefore, if the final decision does not in your competence, try to get him not to delay.