Letter of Recommendation
A letter of recommendation (LOR) provides a reviewing committee with unique insight, stories, abilities, experiences, and character traits about the applicant that will help them make a decision on who to select for an opportunity. This is one of the best areas in which an applicant can stand out from their competition. LORs are commonly required for admission to highly selective opportunities, including institutions of higher education, study abroad, internships, scholarships, grants, fellowships, and many jobs (especially academic).
Your letter writers are offering their professional opinions and the weight of their voices and experience to your application. As such, your letter writers should be people whose opinions have some bearing and will matter to the reviewing committee. For example, if applying for a job in genetics, at least one letter writer should have experience in the industry who can directly speak to your qualifications and suitability for this field and this opportunity. They should be able to speak about direct experience they had working with you either in a genetics-related job, lab, or an academic setting. Ideally, this person will have served as your supervisor or instructor. If none of your potential letter writers have that sort of experience either in the industry or with you, choose people who will be able to talk about specific qualities, experiences, interests, or character traits that contribute to the overall message of "this is a qualified applicant who will be an excellent recipient/addition/participant for this opportunity."
Relationship to Recommenders
Your letter writers should always be people who you know in a professional, volunteer, or academic environment, ideally someone who was in a position of authority over you (such as an advisor, professor, or manager) or was in a comparable position (coworker, fellow volunteer), although that is less desirable. Unless otherwise stated or relevant, a letter writer should never be a family friend, relative, neighbor, classmate, romantic partner, etc... If you are having trouble with finding enough suitable letter writers, a good option would be to volunteer or find a short-term job opportunity to make those contacts. Especially if you are a student or returning to the job market after a long hiatus, it is understandable that your letters may not be as strong or relevant as someone with more recent experience, and that may be taken into consideration by the reviewing committee.
There are cases where the best qualified letter writer may not be the best choice. This is particularly the case if you had a poor experience with them, if they have given you reason to believe that their letter would not help your application, if you suspect their opinion will not be respected, or if you believe that they would not submit a letter by or soon after the deadline (there is often a buffer for late letters, but that is not always the case). Depending upon the reason and whether you have other options, it may still be worth approaching the person and asking if they would be willing to write you a letter. They may ask for more material from you, such as a piece of writing related to the subject matter, your statement of purpose, or a sample LOR that they could build upon. If meeting the deadline is an issue, you could try moving up the "submit by" date, sending them polite reminders, or let them know if the opportunity has a clearly written policy on not accepting late materials (this is often directly stated on the website). Nonetheless, it may be in your best interests to rank a problematic recommender's letter lower, use them as a backup, or replace them with someone else entirely.
Weighing Name Recognition vs. Direct Interactions
As part of the reason for the LOR is for the letter writer to provide the weight of their professional name and opinion, it can be attractive to ask for a letter from someone who is famous and with whom you have a tangential connection. For example, if you interned on a political campaign and you can get a signed letter from the candidate, that signature could certainly attract a lot of attention. If you were applying for an opportunity in politics, then that would probably be a valuable letter to have, and it might even look strange not to have a letter from them (you could also amend a non-confidential statement from the campaign to your resume/CV). However, those letters tend to be very shallow in content, often doing nothing more than confirming your experience with them, the type of work you did, and a generic statement about your being a hard worker. In this case, a letter from your supervisor on the campaign would probably provide more detail on the quality of your work, your work ethic, specific examples of your contributions to the campaign, and an assessment that may not be as flashy but that will have more substance. Depending upon the opportunity, that may be the more valuable letter. On the other hand, you could have a close working relationship with a TA who would be able to provide a great deal of information about your research interests, work ethic, or quality of your writing. If applying for a graduate program, though, that TA's name would likely not have the same power as a professor's would, even if you did not interact with the professor very much. In this case, you may want to reach out to both the professor and TA (if possible) about their writing a joint letter. Or, alternatively, offer to meet with the professor and provide them with materials from the course or even just send them your application materials to see if that would be sufficient. If you still have the contact information for the TA, they may still be a valuable letter writer, depending upon the opportunity.
Prepping Your Letter Writers
The types of materials that you should provide to your letter writers can vary upon their preferences, how well they know you, the opportunity for which you are applying, and whether or not this is the first letter that they are writing for you. At the very least, every request should be accompanied by an up-to-date Curriculum Vitae (CV) or resume. If this is the first letter that they are writing for you or if this is a different type of opportunity compared with previous letters, you should provide them with a draft of your statement of purpose (SOP), your cover letter, and any other written content. Your request should also tell your letter writers three things: 1) why you are pursuing this opportunity, 2) why you think you are well-suited to this opportunity, and 3) how this opportunity fits into your future career, academic, or personal interests. If you are applying to a graduate program, make sure your letter writers know which program, what you intend to study, and any notable people you would like to work with there. If there's a clear connection between this program and a course that you took with a letter writer, make sure they know that, too. Their letter will be particularly important. If you have not interacted with a letter writer very much or not for a very long time, you may want to offer to send them a copy of a paper you wrote for their class (preferably with their remarks, if available) and/or offer to meet up with them in person or virtually to talk over your application.
Pledge of Confidentiality
Under the Family Educational Rights and Privacy Act (FERPA), any student applying to a US institution has the right to review a letter of recommendation. However, many letter writers and reviewing committees strongly prefer that the letters be confidential, to the point where a non-confidential letter may either be evaluated at a lower standard or the contents may be changed with the knowledge that the applicant will be viewing it. Some letter writers may refuse to write a non-confidential letter of recommendation, and if the opportunity is not covered by FERPA, a non-confidential letter might not be accepted by the reviewing committee. If you have faith in your letter writers, you should waive your right to see the letters. If you do not have faith in them, then ideally you should either talk your concerns through with them or find different letters writers.
Writing Your Own Letter of Recommendation
In some cases, a letter writer might ask that you draft your own LOR and they will either sign it or use that as the basis for their own letter. These types of letters may not be as good, especially in the former case, as an applicant is not likely to know the right kind of language to use. Additionally, if you know that your letter writer is not changing the letter that you wrote, that may contradict the pledge of confidentiality you may be asked to agree to when submitting your application. In that case, you may want to reconsider the value of that letter and whether or not it would be better to find a different letter writer. That said, writing your own letter of recommendation could be a good exercise in preparing an application, or it would give you an opportunity to talk about an experience, quality, or other attribute that you are not sure would otherwise be addressed. This could be a great exercise for a first-year college writing course, for example, in order to help students think ahead to the future and consider how they would love for a professor to speak about them in the future. In general, the language should be overwhelmingly positive, especially for opportunities in the US. Start by asking yourself what you want to make absolutely certain that the reviewing committee knows about you as a result of this letter. This should include not only dedication to the subject matter, but also relevant courses, skills, experience, and traits that make you especially well suited for this opportunity. Determine the type of tone you want to convey. If this feels hyperbolic, then stick to practicalities and figures. How many years have you studied a relevant topic? What percentage of the class do you think you fit into? What types of adjectives or descriptions do you wish a professor or supervisor would say about you? Also, check online for sample LORs to determine language, layout, and flow. The Professor is In website has a very useful list of tips and recommendations. And, as with the Statement of Purpose, make sure that the LOR provides a good argument for fit and suitability.