Fast follow up emails after the interview are better than handwritten notes
Lots of job seekers underestimate just how important it is to say "thank you"....for the time, for the conversation, for the opportunity to meet. And it's also important that you get it to your interviewer fast: within 24 hours of your interview. A handwritten, snail-mailed note just won't do that. Send an email.
Why is it so important?
Hiring decisions (or decisions to offer a second interview) are often made very quickly. You don't want to lose an opportunity to sway their opinion in favor of hiring you.
What should it say?
It should address how much you appreciated the opportunity to meet with them, how much you enjoyed learning more about the organization, how you think your XYZ will really help them with their ABC, and how you’re looking forward to talking with them further.
Who should you send a note to?
Send a thank you email to everyone you speak with. They will be talking to each other about you, comparing notes. So make sure everyone you speak with gets one, and make sure they are tailored to the person you're writing it to about the conversation you had with them. A 'form letter' thank you is almost as bad as no thank you at all.
Get my Follow Up After the Interview podcast for no-fail follow up tips.