Four things you need to do after the interview:
1. Thank you: Quickly after the interview, send a "thank you" note to each person with whom you spoke, thanking them for taking time out of their busy schedules to spend a few moments with you. Do not put this off - timing is everything! In today's environment of heavy email usage, hand-written notes can differentiate you from your competition.
2. Post-interview self-analysis: Answer the following questions to evaluate your performance, and make improvements for the next time you interview.
A. What challenges did you face?
B. What could you have done differently?
C. What did you learn during the interview?
D. What do you need to learn for future interviews?
3. Acknowledge that the process takes time: Give the interviewer(s) time to evaluate you in terms of the open position's requirements. Keep in mind that hiring takes time - the company may have many more candidates to interview. They may have given you a proposed time frame, so do not hassle them before these deadlines. Wait until your thank you notes have been received and give them at least three days before you call them. If, after two weeks, you have not heard anything, keep moving forward, but do not become frustrated.
4. First, not last: Your first interview is not likely to be your last. Often you will need two to five interviews before a decision is made. Be patient. However, do not depend on one job interview - keep searching. The more interviews and offers you have, the more control you have over choosing the right job and the more leverage you have to negotiate with.