Interviewing for a job can be a strong source of anxiety, even when interviewing for an internal position. A key to overcoming this is to be well prepared for the interview. Just because it's an internal interview doesn't mean that you can take it lightly. In their book "Interviewing: Art and Skill," Jeanne Tessier Barone, and Jo Young Switzer were quoted as saying "While college students spend in excess of 4,000 hours studying and attending class to prepare for their careers, the average interviewee spends less than an hour preparing for a job interview. These experts also agree on the reason for the lack of preparation -- job-seekers have no idea what questions will be asked in interviews, so they assume there is no way to prepare." With a little research and practice, though, you can prepare well for an internal interview.
It may seem like since you work for the company you don't need to research for the job or position. However, because you work for the company the hiring manager will expect that you know all about the organisation, especially since you have access to the information. Don't take the task of researching lightly. Rely on facts rather than gossip you've heard from others throughout the company. When it doubt, consult a Human Resources representative for the correct company information.
When interviewing for an internal job, the natural tendency is to assume the interviewer knows you, either in person or by reputation. It may seem awkward to tell them the successes you've had in your career. However, don't assume they know anything about you. Be prepared to treat them like you've never met before. That way, none of your experiences and accomplishments will go unnoticed.
Plan for the Questions
You are competing with well qualified candidates who have just as much access to information as you do. You don't want to seem less prepared than them. When possible try to find out what types of questions they will be asking in the interview so you can plan your answers. In addition, prepare questions to ask the interviewer regarding the position. Failing to do so sends the signal that you really aren't interested in the job.
If you have a shady work history at the company that you fear may hold you back from being successful in the interview, you may want to come clean sooner rather than later. In "At the Interview, Why Not Brag About Your Vulnerabilities?", Joe Turner describes the technique of selling your weaknesses like you would a car. The theory goes something like this. If you have a car with a scratch or dent, you may be inclined to ignore the blemish when meeting with a potential client. However, once he notices it, which he will, he will feel like you tried to pull one over on him and be reluctant to purchase from you because he doesn't know whether you are trustworthy. Tanner suggests that instead you address the imperfection early in the discussion, which tends to diffuse the situation. The same is true for bringing up a less then perfect work history in a job interview.