I always like to send a thank-you email within 24 hours of the interview. It's a great way to follow up and be polite. I generally say something like, 'Thank you so much for taking the time to speak with me yesterday. It was interesting learning about the position at Company XYZ and I look forward to hearing from you soon. If you need anything else from me in the meantime, please don't hesitate to ask.' Grammarly has some more great tips too: https://www.grammarly.com/blog/how-to-write-a-thank-you-letter/ Good luck!

If the interviewer told you that they will get in touch with you soon after the interview, a week is good enough for a follow up. If there is a specific time frame that they have given for follow up and you did not hear anything, that is as good as a no. Regarding following up the interview in person, remember how you read the interviewer. Was the interviewer a busy person? If he was, an in-person follow up may not be ideal, as he would see that as being pressured to make a decision. If he seemed genial and friendly, you may pay him a follow-up visit at your own risk. If you ended up following up with him in person (or by e-mail, which is more ideal and less intrusive), you can say, "hank you for the interview last week. I would like to follow up if you have already made decision regarding hiring (or whatever the interview was for)."