i always make an appointment to discuss the rotation and obtain feedback. i always go in person. i always have a personal statement, cv, and release form in hand. then i talk about the rotation, give and receive feedback. then i ask for a letter. if i go early i say i understand it's contingent on my performance for the entire month, and if something changes then they are under no obligation. i always make sure they are willing to support my application. i always ask for a STRONG letter. hasn't failed me in 10 years.