Beating the other guy to your dream job means nailing the interview.
Interviews don't need to be a stressful experience if you are well prepared; remember, an employer wants to hire you as much as you want the job, you just have to show how much you really want the job, not any job - this job!
Do:
Be on time - aim to arrive 10min before the interview (no earlier)
Turn off the mobile - not on silent or vibrate; off!
Pay attention to personal hygiene - bring some mints, and take one just as you enter the building
Firm handshake & sit upright - first impressions are critical
Speak clearly & confidently - don't rush your answers
Research the company & prepare questions - take a pen and pad, take notes!
Don't:
Tell lies
Rely on the interviewer to do the selling for you
Act as though you just want any job - show them this is the job you really want!
Smoke or chew gum
Look at the time
Start talking about personal issues
Criticize current or past employers