There are a number of concrete steps you can take to increase the probability that a job interview will be successful - i.e., that you will receive an offer or will be invited to return for additional interviews.
Preparation is the key.
Because interviewing is an unrehearsed conversation between two strangers, the discussion can take as many paths as there are people. For that reason, it is crucial to be comfortable with the unfolding of the process. It helps to think of the process as one where both parties are hoping for a positive outcome. Your degree of preparation speaks volumes about your interest level, conscientiousness and ability to plan ahead. Your preparation will also increase your confidence, your ability to answer questions articulately, and your ability to ask discerning and pertinent questions.