The first step in preparing for an interview is to research the company and, if possible, the interviewer.
Your research should include growth trends, products, profitability, the company culture, the dress code, level of informality and communication habits. Use your network to obtain this kind of information in addition to the published research sources you investigate. Obtaining information on the interviewer is sometimes more difficult. Often Google search will provide some information depending on who they are and the nature of the organisation and the individual. The trick is to be as prepared as you can.