Say to the resident or attending "hi Dr. X, I have been trying to improve my notewriting, especially my A&P, etc, and I was wondering whether you can review it with me when you have a few minutes, like at the end of the day or something." Whenever you phrase it in a way that lets them know you're trying to learn and are asking them to help you learn, and give them adequate heads up (i.e. don't expect them to drop what they're doing and read your note right then), I find most people are quite helpful. I just started outpatient medicine, so most of the attendings and residents just had me shadowing because they are so pressed for time and I was getting bored to tears. The second day, clinic was busy and they had a patient waiting in the room and the intern was behind schedule, so I asked if I could go interview the patient by myself until the intern was ready- attending was like sure go for it. I not only got to do the H&P, but got to present to the intern, she was able to see the patient in a much shorter time, and she let me take the lead on presenting to the attending. I know they probably say this to all med students, but the attending was like "nice work getting a thorough but focused H&P , med student." Today, 4th day in clinic I got to see and present 3 patients. On the downside, now that Attending knows who I am he called me in on a couple different cases to listen to a weird case rheumatic heart disease and later a carotid bruit and I totally got pimped both times and wasn't able to answer a lot of his questions, so now he probably thinks I'm a total dunce.
Anyway, I'm imagining it's different in surgery in terms of how many patients you get to follow etc, but from what I've heard, most of the times you have to ask if you want them to let you do something. If you want to present, say "hey resident/attending, I've been trying to work on polishing my presentation, when you have some time can I do a 5 min presentation with you and get some feedback?" Again, not suggesting you be a nuisance, but if you ask a couple times a week they probably wouldn't mind.