Whether for graduate school admission or that all-important first job, a professor's letter of recommendation can be invaluable. Here are some guidelines to follow for requesting (and getting) a good one.

Choose carefully the professor or professors you ask for recommendations. Beyond selecting someone who will write a favorable letter, keep in mind that recommendations from a department chair, a senior faculty member and professors in your major subject area are most impressive and relevant.

Seize the moment. If you really hit it off with a professor in your freshman year, ask for the recommendation letter at the close of the semester in which you took his or her class. By the time graduation rolls around, you may be little more than a face in the crowd.

Offer to write the letter and have your professor sign it. This not only saves the professor time, it allows you to include the information you want in the recommendation.

Follow up. We're all busy, but you are making a legitimate request, so don't be shy about a giving the professor a friendly reminder or two if you don't get the letter in a few weeks.

Make copies! Having to go back and request another letter because you lost it or ran out of copies of the original does not make a good impression.