The contents of recommendation letters are largely out of your hands, but there are still helpful suggestions to keep in mind, especially on choosing and interacting with a recommender to get the best recommendation you can.
Ideally, your recommender should be familiar with not only your academic and research abilities, but also know you as a person. This includes knowledge of your personal interests and background and how these will enhance your research and general educational experience. Having a recommender who was a professor for a course you took freshmen year (along with a hundred other students) is probably not enough unless you did such a stellar job in that course that you clearly stick out in that faculty member’s mind as one of the best and the brightest they have ever seen. Just because you remember that faculty member, does not mean he/she will remember you or not get you confused with another of their countless students. Recommenders should also not just be an important name. A world famous recommender will be of little use if they can’t speak about whom you truly are and/or your potential in the field. Your choice for a recommender hopefully should have the time required to have relevant discussions with you as well the time to draft the actual recommendation. Will the faculty member be travelling, on sabbatical, working on their new book etc.? Working closely with faculty on a daily basis, department officers and administrators often have more information about faculty members’ time constraints than you will, it is therefore important for you to inquire with these individual on your recommender choice if possible and ask for advise accordingly.
Similar with the need for time to draft the recommendation, you should also think about whether a faculty member answers emails in a timely fashion (or at all). It is important to remember that a recommender is also working within a deadline and you should make sure you both reach it on time. One of the largest reasons for failed fellowship applications is that a recommender doesn’t send their recommendation in by the deadline. Even if your recommenders are incredibly diligent and organized people, you should always be sure to follow up and remind them of their obligations. Faculty are busy, emergencies happen, people travel etc. but these shouldn’t be reasons you don’t get a fellowship.
Providing recommenders with the necessary information to draft thorough and impressive recommendations is important. The more information the recommender has the better the recommendation will be. You shouldn’t just ask or expect a blanket recommendation. You deserve more than that! You should send your recommenders any relevant “information for recommenders” provide by the fellowship organization (deadline, formatting or other guidelines, specific questions that should be addressed etc.), as well as an updated CV, your academic record, your proposed course of study and area of research, a draft of your research proposal and perhaps even your personal statement (especially if you don’t know the person well). Being thorough and organized here will likely impress your recommender and make their job easier (possibly influencing a better recommendation). Along with paper documentation, you should also try to have actual discussions with your recommenders. At this point, you should have done your research on the fellowship/s you are applying to, so you should inform your recommenders of what the fellowship organization is looking for (selection criteria, goals, targeted types of people, backgrounds etc.). This is also a chance to discuss your research topic in detail. This will not only give their recommenders the information they need for the letter, but may also help you clarify your research proposal. This is also a good opportunity for you to ask for feedback. You should also not be afraid to make suggestions of things a recommender can include in the recommendation. You may already have a close relationship with your recommender, but it doesn’t hurt for you to remind him/her of your background, strengths, and accomplishments. Faculty time is important and they are often very busy people. You may not have another chance again to have such an extensive exchange like this in the future. Milk it for all it is worth!