Interviewing for an internal promotion is a double-edged sword. On one hand, you know the company and, probably, the people you're interviewing with. On the other hand, this familiarity can make you overconfident, or make you so comfortable that you forget to truly sell yourself for the position. One way to make sure you ace your promotion interview is to approach it just as you would if you were seeking a high-profile position at an outside company.
Find out the specific job requirements for the position. Even if you think you know what the job entails, talk to your human resources office and get an official job description. In the event the company is also interviewing external candidates for the role, knowing the exact criteria you'll be measured with can help you prepare. Also, ask around and find out who else inside the company is up for the job. Knowing your competition and the skills and experiences they bring to the table can help you better establish yourself and prepare you to highlight what you have to offer that your colleagues don't.
Think of the interview as an opportunity to sell yourself as the best person for the position. Go into the meeting prepared with statistics that demonstrate your effectiveness in your current position. Quantify your contributions wherever possible, for example, discussing new procedures or policies you spearheaded, major projects or initiatives you handled, and financial savings or earnings you were responsible for. Also bring along positive performance reviews or letters of commendation you've received in the past.
Arrive for your interview on time and dressed in your professional best. Internal candidates sometimes make the mistake of going into a promotion interview in the casual business clothing they usually wear, which doesn't set them apart or position them as management material. Dress the part and take on a bit of a professional air, even if you know the interviewers well. Decision-makers need to see you in a new, authoritative light.
Promote yourself in the interview by showing your enthusiasm for the challenges and opportunities the position presents. Use the job description to put together thoughts and ideas for how you would approach the first few weeks in the new role. This shows you’ve given thought to the responsibilities of the job and are prepared to hit the ground running. If you have particular abilities your competition lacks, emphasize those in the interview, too. While you don't want to put down your colleagues, you do want to position yourself as the best person for the job.