Research the company.
Do some basic research on the company you are interviewing with. They will expect that you have looked at their company website before coming in. If you are meeting with a recruiter, make sure you don’t pigeonhole yourself. The position you are coming in for might end up not working out and you may be a better fit for something else. It helps if you have different versions of your resume. 

-Prepare for questions about your career.
You should have an upbeat and cohesive story relating the progression of your career (credibly explaining any gaps in your experience) and the direction in which you see yourself heading.

Be sure to express why you are pursuing a consultant opportunity at this time (to alleviate any unspecified concerns the interviewer might have that you are still looking for permanent work and will leave shortly into the assignment).

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Regarding the interview.
More and more companies are using behaviorally-based questions for part (or most) of the interview. Be prepared to answer behaviorally-based interview questions.

Prepare questions to ask during your interview. If you can’t think of any specific questions about the position, you can always ask general questions about the company such as the corporate culture, the management style, the qualities a person might need to flourish in the job, etc.