Letters of recommendation are tools that can take a maybe applicant and make them outstanding or take an outstanding applicant and make them unsuitable for the program. Letters of recommendation are typically not allowed to be viewed by the person who is requesting them. That being said you must ensure that the person you are requesting to speak about you candidly behind your back, will in fact, have your best interests at heart. Don’t ask the professor you had freshman year in the 400 person lecture whom you never spoke to, to give you a letter of recommendation. Most would (or should) say no or recommend you ask someone who knows you better. For the few that don’t I can promise that the letter will not be as strong as it should be, depending on the person it could even be negative. You want to ask people who are in good standing in the field you want to work who know you personally and academically and are happy with and believe in you. Also please remember that it is a matter of professional courtesy to give the letter writers at the very least a month’s notice that you are requesting a letter from them. Provide them with your CV and inform them of your plans and dates. You are allowed to check in on them as time progresses but no one likes to be pestered. Good luck.