After an interview
One applicant said he'd have the company's logo tattooed on his arm if he got the job.
There's no need to copy him. Just end the interview with a strong handshake and thank the interviewer for his or her time.
Reconfirm your interest in the position and ask if you can telephone in a few days to check on the status of your application.
If the interviewer offers to contact you, politely ask when you should expect the call. Follow up with a phone call if you are not contacted within a week of when the interviewer indicated you would be.
Maybe send a brief ‘Thanks for the interview’ note. Try to time it so it arrives before the hiring decision will be made – this will remind the interviewer that you're suitable for the position, so feel free to mention any topics discussed during the interview.
In the (unlikely) event of you NOT getting the job, don't get disheartened. These things happen and there will be another position around the corner with your name on it.
In the meantime, give the company a call or write to them and ask for some feedback on your interview – you will be able to work on any negative points and correct them at your next interview.