What makes a good letter?
Recommendations are particularly valuable if the person writing the letter is known to the committee, either personally or by reputation. A big name in the field, someone famous for top work, is much more valuable to you than an obscure teacher. However, don't panic if you can't get a big-name recommendation-a praiseful, well-written letter from a lesser light who knows you well can still be a tremendous asset. A detailed letter from a less well-known teacher is better than a perfunctory letter from a big name who doesn't really know your work. Moreover, the faculty on admissions committees know that it is often difficult for students to meet the big names. One professor said, "Eminent persons
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Model Letter
Strategies for obtaining Letter of Recommendation
What if you don't have a Recommender.
from Harvard or Yale rarely write because they don't teach undergraduates. At Princeton and Stanford it does happen."

The ideal letter of recommendation speaks specifically to your strengths and describes enthusiastically what sets you above the pack. Valuable letters praise your quickness of mind, maturity, self-direction, organizational ability, speaking skills, determination, and research ability, and use specific examples of your successes rather than vague generalities.

Some schools give you the option of "open" or "closed" letters, "open" meaning that you can see them before they are sent out, it is recommend that you take the "closed" option. Studies have shown that letters of recommendation are more flattering when they are open to the student, and admissions committees know this. Therefore, committees devalue an open letter. If you worked hard to deserve a good recommendation from a teacher, then you don't want a committee doubting the letter because you have had an opportunity to see it. If you doubt the quality of the letter you will get from a teacher, you shouldn't be asking him for it anyway.

Choosing Your Recommender's Schools:
Most schools require 2-3 recommendation letters. Choosing the appropriate mix of recommenders largely depends on the program you are applying for. For an MBA program, two recommendations from work and one from school is generally a good balance. If the school asks for only two recommendations, it would be advisable to get both work related. As far as possible, it is advisable to get one recommendation letter from your immediate supervisor. However, if it is not possible, then a former supervisor would be a good choice. As a last alternative, you could use a colleague who has worked closely with you. It is not advised to apply without a recommendation from your current job place. For more details, check out the recommendation letter section on the MBA channel.

Graduate Programs:
For an MS or Doctoral program, you should get at least two recommendations from your professors. If you have performed research or worked on thesis, it is highly recommended that you get the reference letter from your Advisor. If you worked for a company either full time or as a summer intern, you could take one letter from your immediate supervisor.

Undergraduate Programs:
For candidates applying for an undergraduate program, very few schools ask for a recommendation letter. If asked, you should get it from one of your favorite teachers in school.

Some other points to keep in mind while choosing your recommender:

Choose people who know you well. Rather than choosing a famous person who has no intimate knowledge of your skills and abilities, it is much more powerful to use a person who can illustrate your strengths and show you at your best.
Choose people who really like you. It is important that a recommender invests time in writing your recommendation. A person who likes you will take out the time as well as put a positive spin on your qualities.
Choose people who are able to express themselves well in writing. If the recommender isn't fluent in written English, have them write in Urdu or whatever language they are used to, and have the letter translated (an attested translation). Someone might be a great teacher, and really like you, but if they are unable to write well in English the recommendation may come across sounding mediocre just because of poor language skills.
Choose people who can address more than one key criterion: your business and managerial skills, intellectual ability, leadership potential, maturity, work ethics etc.
Give your recommender an outline of the assignments you have handled at work. Include in the outline some suggestions on how he/she might address specific issues such as analytical ability, integrity, intellectual curiosity etc.

How to write a letter of recommendation
Initially, the letter of recommendation should identify its author in terms of academic background and professional experience. If the author has been associated with the American educational system, whether as a student, professor or researcher, this fact should be mentioned. The person who has had a university experience in the United States is better able to objectively evaluate a student's possibilities for success in that academic system.

Following this, the existing relationship between the author of the letter and the candidate (professor/student, researcher/assistant, employer/employee, etc.) and the duration and nature of the contact should be specified by the author of the letter. For example:

"This candidate was my student for two semesters, in a theoretical laboratory course in the biological sciences, which had as its objective to introduce genetic and molecular biology to biology students. This course, one of the department's most rigorous, awards four credits. During our association, I had the opportunity to become well acquainted with the candidate, and this permits me to make a prediction with regard to his performance in the American academic system".

The letter should evaluate the candidate's level of ability and performance, from the specific in relation to other participants in the same group, to the general in relation to the norms of a specific academic or professional area. For example:

"The candidate impressed me as an extremely capable and above average student. Among the group of thirty students, I would not hesitate to consider him one of the two best in the class. The student's academic performance and participation during the course revealed an ability to think logically, intellectual curiosity, commitment and critical thinking. In addition to these characteristics, he consistently demonstrated a highly developed creative ability while he was my student".

A letter should also mention the candidate's personal traits - leadership ability, maturity or others if the author has had the opportunity to observe these. Finally it is important for the letter to emphasize the relevance of the foreign program of study to the professional possibilities in the candidate's country.

Note: To maintain the confidential aspect of the letter, it is preferable that the author of the letter and not the candidate send it directly to the university. Therefore, when you ask someone to write a letter of recommendation, it is strongly recommended that you provide them with a stamped envelope addressed to the institution to which it should be sent.

The letter should include:
The recommender's status -- position at the university or job title. How long has he/ she known the student and in what capacity (as a teacher, an adviser, a research supervisor, etc.)
The better the recommender knows the student, the more effective his/ her recommendation will be. They want specifics, NOT generalizations. It is good to say that someone is hardworking and organized, but you need to back up these statements with concrete examples. "Julia is a hardworking student. Her research project on unemployment in Akademgorodok was thorough and was an impressive demonstration of her ability to work with and analyze statistics." Talk about what the student has done and is capable of doing. What is it exactly about the student that makes her or him special? Why do you think this student would benefit from studying in the U.S.?
Evaluate the student by comparing him or her with other students you have observed in your work. The following is a suggestions of categories you may wish to use for comparison. You can use phrases such as excellent, very good, average, or below average.
 
Intellectual Ability Work Habits
Teaching Potential Seriousness of Purpose
Knowledge of Field Emotional Maturity
Resourcefulness and Initiative Adaptability to New Situations
Motivation to Pursue Graduate Study Potential for Significant Future Contribution in Field
Quantify your impressions. Is the student in the top 5% of his or her classmates, top 10%, 25%, 50%?

One page is sufficient. Quality, not quantity, is what is important. Make every sentence count. Do not put something in if an immediate connection cannot be made between that information and the student's ability to participate in the program.

Technically, students are not supposed to see the recommendations, but the student must ensure that everything is mailed. Most schools ask that the recommender put the letter in an envelope, seal it shut, and sign over the seal.

Letters of recommendation vary widely in content and form, but solid letters contain a number of common traits. Here below is an outline for a well-structured letter that covers all main points.

Introduction:

 First Paragraph:
Introduce yourself, begin the letter by clearly stating your position, where you work, your relationship to the applicant, and how long you have known and/or worked with the applicant.

Second Paragraph:
Give your general impression of the applicant.

Body:

Third Paragraph:
Applicant Quality # 1. State the applicant's most noteworthy quality and support that claim with a specific anecdote. For instance, you might say that Samantha is, first and foremost, a born leader; then, support that statement by telling about the time Samantha took the initiative to form a task force to deal with a glitch in the company's computer accounting system.

Fourth Paragraph:
Applicant Quality # 2. Again, state your claim with specific anecdotes and concrete examples.

Conclusion:

Sixth Paragraph:
State why you think the applicant's plans suit him/ her.

Seventh Paragraph:
State how you think the applicant will contribute to the program or company.

Last Paragraph:
Strongly reaffirm your confidence in the applicant's abilities and conclude by telling the readers they should feel free to contact you in case they need more information. Don't forget to include your contact information beneath your signature and name.

Notes about the format and length:
Don't handwrite the letter; type it. Handwriting a letter is a sign that you are not serious about the task and will reflect poorly on the applicant.

Remember to use official letterhead, to sign the letter and to include both complete contact information. When you have folded the letter and put it in an envelope, sign across the seal.

The length of letters of recommendation varies greatly, but five paragraphs is usually the minimum. On the same note, don't go overboard and churn out seven pages, even if you are highly enthusiastic about the candidate. Choose your content wisely, and remember that a concise letter is usually more effective than an overly verbose one.