Think of concrete examples you can use to highlight your skills. Providing evidence of your successes is a great way to promote your candidacy. Also have a list of your own questions to ask the employer ready.
Do your homework about the employer and the industry. Know the interviewer's name and use it during the job interview. If you're not sure of the name, call and ask prior to the interview.
Bring a nice portfolio with copies of your resume. Include a pen and paper for note taking.
If you interview with multiple people send each one a personal thank you note. Send your thank you note (email is fine) within 24 hours of your interview.
Dress for Success. Remember that it's always better to be overdressed than under -- and to wear clothing that fits and is clean and pressed. Keep accessories and jewelry to a minimum. Try not to smoke or eat right before the interview -- and if possible, brush your teeth or use mouthwash.
Be Authentic, Upbeat, Focused, Confident, Candid, and Concise. Provide solid examples of solutions and accomplishments -- but keep your responses short and to the point.