Writing letters of recommendation is a relatively new responsibility for me, and it is one of the central duties of my profession. When requesting a letter of recommendation from me, please consider the fact that unlike more senior mathematicians who have done this hundreds of times, I am new to this game, and, following Ravi's advice, it is in your best interest to make my job as easy as possible.
Procedural aspects:
Contact me via email to request a letter of recommendation at least 5 weeks in advance of your first deadline.
Shortly after this, we will meet, either in person or over phone, to discuss if I am a good choice for you. If I feel that I am not able to write a strong or compelling letter, I will tell you as much. This reinforces the 5 week deadline above - you will want to have ample time to find a replacement.
If I agree to write a letter please send all supporting documents and a list of programs/jobs where you will apply with deadlines (I used a two column list to do this as an undergraduate) one month before the deadline. Please also give me a heads up about non-standard letter procedures, such as having to send things via physical mail or special websites.
In a single PDF file, please send me the following documents and answers to the questions.
Questions:
What is your name and preferred personal pronoun?
In what capacity and for how long have we known each other?
What aspects of yourself should the letter address? What do you self-assess as your strengths as a mathematician?
Are there highlights on your CV that I should pay special attention to? Are there non-standard circumstances I should be aware of in reading your file?
What are your long term goals? If you are applying to graduate school, do you have an area of mathematics that you are especially interested in?
If you are applying for an industry job, what aspects of your being should I address?
Documents:
CV
Undergraduate Students: transcript (an unofficial one is perfectly fine)
Undergraduate Students: a list of your mathematics classes and a short description of the classes themselves (i.e. don't make me look up what Math 380 at your university is, just tell me you took abstract algebra)
Research statement.
copies of any papers or theses you have written, or working links.
If your letter has not been submitted within 24 hours of a deadline, please send me a reminder. Also, sometimes graduate school applications do not request letters from recommenders until the applicant has submitted the application. Do not put me in a situation where being away from email for 24 hours will make me miss a deadline. Corollary: The problem does not arise if you submit your application more than 24 hours before the deadline.