The core of your preparation for the job interview:

  1. Learn what they do.
  2. Learn how they do what they do.
  3. Figure out exactly what skills, experience and background you have that will help them do what they do faster and cheaper.
  4. Plan how you're going to explain #3 to them.

Everything else is implementation details.

You should have the first three figured out before you even send a resume. If you don't have what it takes to help them do it cheaper and faster, then don't waste your time applying for the job.