You’ve heard it a million times: Always send a thank-you letter after a job interview. So it may surprise you to learn that some hiring managers don’t like receiving these letters. It’s a waste of their time, they say.

Sounds a little curmudgeonly, doesn’t it? But maybe it’s because so many thank-you letters are a waste of time--theirs, and ultimately, yours, too. Are you using your letters just to say “thanks for the interview”? Then you are throwing away a golden opportunity to strengthen your chances of getting hired.

Help stamp out weak, ineffective, generic thank-you letters. Start writing turbo-charged thank-you letters that impress potential employers and earn you job offers. How?

For starters, your thank-you letter needs to be more than a simple "thank you." Think of it more as a “follow-up” letter. What did you talk about in the interview that you can enlarge upon, add to, or extrapolate from? A good thank-you letter continues the conversation you began in your interview. This is the time to add a point you forgot to make or to emphasize anything that needs emphasizing.

At the very least, you should recap why you want this job, restate your qualifications, and reiterate the contributions you could make to this employer. Just because you talked about it in the interview doesn’t mean the employer will remember it later.

Maybe you can find a clipping of an article that would interest your interviewer, or that builds upon a point covered in your interview. It lends more interest and heft to your missive and makes it more memorable than just a one-page thank you. Put yourself in your interviewer’s shoes and ask, What would enlighten, delight, inform me? What would I appreciate receiving?

In fact, the time to start thinking of what you’ll put in your thank you letter is during the interview. You can and should be looking around the place for things you can comment on later. Did the receptionist seem particularly alert and pleasant? Were the offices/facilities outstanding in some way? Did you and the interviewer bond over a hobby or interest you have in common? Make a mental note and mention it in the letter.

Most of all, your thank you letter should sound like you. You are trying to remind the hiring manager of who you are, to distinguish yourself from all the other applicants he or she may have spoken with that day. So whatever primary impression you make should be reinforced in the thank-you letter. Are you trying to sell yourself as enthusiastic and positive? Your letter should reflect that. Is a businesslike and crisp presentation your strength? Your letter should be the same.

This is why you need to write your own letter. Sending a thank-you letter copied from a template you found on the Internet is almost as bad as not sending one at all. It’s worse if your interviewer is receiving the same letter from other applicants! Another major no-no is a letter with typos, grammatical errors, and misspellings. If writing is not your thing, please get help from someone for whom it is.

What about those other vexing thank-you letter dilemmas? (E-mail or U.S.P.S.? Typed or handwritten? Does it absolutely positively have to be sent within 24 hours?) Here you have some flexibility. If you are interviewing with a very traditional company, and/or if your interviewer was significantly older than you, make your thank-you letter correspondingly formal. If the interview and company had a casual feel, and especially if your previous communication was via E-mail, then an E-mailed thank-you letter should be fine. As for when, sooner is usually better than later. But, as in all matters of communication, consider your audience.

A thank-you letter is not just an empty exercise or outdated form of politeness. It’s a powerful sales tool. Make yours work for you.