Most graduate school admissions committees require 3 letters of recommendation from faculty who know you well and can attest to your ability to succeed in graduate school. If your only experience with a faculty member was in a class in which 80 other students were enrolled, the person may not be able to say much about you, even if you came to class regularly and earned an A. So, get to know them by participating in class, visiting with them during office hours, talking with them about careers and graduate school, and assisting with their research.
When requesting letters, first ask the people if they would be willing to write you a favorable recommendation. Then, six weeks before the deadlines, provide the writers with an organized packet of materials with information about you (your resume with contact information included, a current copy of your transcript, and a statement of your career aspirations) and with information about the graduate schools. In a cover letter, for each school, identify the program to which you are applying, the application submission deadline, whether an additional form must be completed, and whether the letter should be mailed directly to the school or returned to you in a sealed enveloped with their signature across the flap. As to additional forms, most will have a section that you must complete before giving to the writers. If asked to indicate whether you waive access to the letter of recommendation, answer affirmatively (that you do waive the right) so that the letter will be seen as genuine. As to envelopes, include a stamped and addressed envelope if the letter should be mailed directly, or include an envelope with your name and the school’s name on the outside if the letter should be returned to you.