Thank you note

It may be accepted to email but a hand written one will stand out and be more memorable, as few are likely to do it and hiring managers in-boxes tend to be packed full. The ability to write an old fashioned thank you note is always appreciated and is a dying art.

Would it be acceptable to have the thank you card with me when I go to the interview, fill it out immediately after, and give it to HR before I leave?

And how formal should it be in the language?

Do I just use a general blank card?

Don't give it to HR. Mail it to the hiring manager who interviewed you - on your way home from the interview. It should be formal. This is a formal matter. Unless you got the impression that the manager is a swingin' kind of person, not at all a stuffed shirt or formal person. You know, sort of like Southwest Airlines' atmosphere seems to be. Sure, use a blank card. Why not?

A thank-you note should be fairly formal ... and if you decide to do both an immediate e-mail and a hand-written not through snail mail, then the two messages should be different. Think of what it is like to be receiving the identical message twice within the span the of 2 or 3 days -- not good. Think of two different things to say.

For example: In the first message -- an e-mail sent immediately after the interview -- you could be very brief and thank the person for their time and say how impressed you were with their unit. Then in the second message (actually sent the same day, but arriving a day or two later), you could expand on your thoughts a little, comment on another aspect of the job, or ask a question. (Be sure to include your contact information at the end of that thank-you note.)

Good luck.