What single thing can you do AFTER an interview that could help you land the job? Send a thank you note! Whether you type or write a handwritten note, saying thank you for the time the interviewer(s) spent with you sets you apart from the great majority of interviewees. If you can, add some additional information about why you are a great fit for the job based on what the interviewer(s) communicated, and all the better.
Written or typed, get that thank you letter done and mailed the same day as the interview. Your memory is best when information is fresh, and your notes will make the most sense immediately following the interview. By mailing (not emailing) your thank you letter to the interview(s) quickly, you show them how serious you are about the position and avoid the issues that email causes, including the thank you letter going to a spam folder, the interviewer not recognizing your email and deleting it, and the fact that we typically only skim emails, but read something coming across our desk more thoroughly. Make a great impression - say thank you! To your job search success!