The letter provides one last opportunity to stand out among your competition. At the conclusion of the interview, you should find out how long you can expect to wait regarding an employment decision, and feel free to contact the company to check on delays if you don't hear within a few days after the estimated time. Don't be afraid to turn down a job offer if, after careful consideration, you feel it is not the right step for your career goals. If necessary, do so in writing and courteously, since you never know what personal and professional ties this organization may have with others in your field. Don't apologize for shortcomings and avoid any comment that can be construed negatively.
Negative information is weighed more heavily than positive.
Use relevant examples. Interviewers hate to feel as if they're dragging information out of you. Along those same lines, remember that if something appears on your resume then it is fair game to be discussed in the interview. Keep yourself current. Rather than give a poor answer, ask for a minute to think about it, then give a quality response.