Employers want to know three key things: can you do the job, do you want the job, and will you fit into their organization? Most candidates focus only on the first of these: make sure you have compelling answers as to why you want to work for this particular company as opposed to one of their competitors, and why you believe you will be a good match for their working culture.  Try to gain an understanding as to what challenges/problems this role will be focused on and how you help them solve these issues.