Have you ever repented of a wrong choice that you've made on the interview? If you haven't then you've done not enough screening or you are not a human being :)
To begin with, interviews last for about 40 minutes in average and the mission is to get to know a person. I doubt it can be done in such a short time to the full extent despite all the efforts. As we know a person reveals best in the specific circumstances, the ability to cope with stress is only visible under stress, the ability to play in a team can only be seen in a team. But we cannot simulate all those conditions This means that we have to use the only means that we have at hand.
First of all, we ask questions and evaluate responses. It gives us some idea on the type of a person that we talk to. But this is only a part of the full story. The most important is to watch the person carefully and see what his or her body and mimic tell you. Body language can speak better than a candidate himself.
By paying due attention to not only what is said but how is said by a interviewee, you can even learn whether what is said is true or lie. Changes in the intonation, strange abrupt movements, grimaсes, looks sideways - are the clues to note.
Another thing to do is to compare what you are told with what you see. For example, if a candidate is wearing a stained clothes but keeps telling you about how diligent and accurate he is, you have a good reason to doubt the words. There should not be any conflict between your perception of a candidate and the story that he tells you. If there is any, don't hesitate and ask at the interview. Not doing it would be a big mistake and means only the postponing a problem for later.
Last but not least, always trust your sixth sense. Never give job to someone to whom you have the slightest disbelief. I did it myself in the past for a few times and I regret it later pretty much. To my credit I also rejected much more candidates only based on that slight doubt and I never regret any of those choices. So, this is obviously more painful to make a wrong choice then not to make the right one.
Hope this helps all of you who are looking for bright minds over there!