my school's IM clerkships/exam grading policy sux
so my medschool grades the shelf by percentage, not percentile. You literally have to get a 90%, to get Honors, not 90th percentile. Pretty ridiculous, IMHO... I got a 85% on the shelf, which excluded me from getting Honors, unless I got above 95% on the clinical evaluation (also nearly impossible).
Plus we only had internal medicine for three weeks (technically it's a six week clerkship but the first three weeks were spent in a Family-Medicine-style outpatient office, where I learned essentially nothing but the business end of medicine, and nothing for the shelf.)
Nevertheless, I managed to get an 85%. This is how:
1. Step Up to Medicine. I read all of it, during the two weeks before the exam. Reading all that in two weeks was hard, but definitely worth it. Pay attention to the Diagnosis and Treatment section after each disease entity. The shelf is essentially full of questions that ask, "What's the next step in management?", "Which test would confirm your diagnosis?", "What's the most appropriate treatment?" There was only one question that I recall which asked for the pathophysiology or mechanism of disease (reminiscent of Step1).
2. I did MKSAP2, once. Use the CD and do it on the computer. The questions were similar in length and complexity.
3. Read fast, time is not on your side. Don't read every word in the question. Skim. We were given only 2 hrs and 10 minutes.
4. Most importantly, I felt you really can't study for the shelf (this is coming from someone who usually studies and worries and obsesses a lot before exams). The best thing to do is be alert as possible on the wards, pay close attention to your team's patients, closely follow the attending's reasoning on why order this and that test, and try to answer the pimping questions. Look up stuff on your assigned patients and any other interesting cases assigned to other people (you can keep the latter to yourself so you won't come off like a total ass-kisser).