Finding a job is a matter of preparation. You need to be prepared to have an intelligent conversation with your interviewer. If you are visiting with a telecom banker, be ready to talk about the telecommunications industry and its future. If you are visiting with a fixed income derivatives trader, be ready to talk about duration, convexity, swap spreads etc.

Pick one or two focus areas and work hard on them. Read books. Follow the trade press. Surf the web for further information. You will want to know more about the vertical area you are pursuing than the average well prepared MBA student out of a top business school.

Nothing impresses an interviewer more when they meet someone who is truly prepared to go forward in an area, has deep vertical knowledge and checks the boxes for job suitability which generally are:
  1. Knows the field
  2. Indicates ready to work hard
  3. Connects personally
  4. Presentable and well dressed
  5. Articulate
  6. Fields a technical question or two well
  7. Raises some strong points while maintaining an intelligent conversation
  8. Asks good questions
  9. Smiles and maybe makes a joke or two
  10. Shows humility and is quick to say "I don't know" when they don't.
  11. Doesn't wear suspenders or have heavily gelled slick backed hair (a la Michael Douglas in Wall street)
  12. Demonstrates integrity and authenticity
How To Prepare For An Investment Banking Interview
Here are couple of useful tools for you.

First, view this
Goldman Sachs interview skills video which provides valuable tips and hints. It's short and precise. Make sure to spare a few minutes and go through the entire video.

Next, browse this list of
questions from Morgan Stanley and prepare your answers.
The questions you are being asked all depend on the interviewer. However some questions do come up more frequently than others. Here are the most popular questions which do worth your time preparing for. I have included some guidelines while preparing your answers.
Describe any of your personal achievements/extra curricular activities you are particularly proud of and why.
Your answer should include a situation where you demonstrated Leadership

Why did you choose to interview with us (Citi e.g.)?
Make sure you know the company and the position. Describe your motivation for wishing to work for Citi; the actions you have taken to learn about Citi and what key skills you possess that would make you a suitable candidate for the business area you have chosen. Make sure to have Clear Evidence of Motivation in your answer.

Describe a time when you have successfully solved a challenging problem or overcome a difficult situation.
Your answer should include a situation where you demonstrated Problem Solving Skills preferably with Commercial Judgement.

Describe a time when you have presented a persuasive argument to a group of people which resulted in a mutual outcome.
Your answer should demonstrate your skills of Influence & Persuasion. Make sure your situation ended up win-win.