In order of usefulness (for me):
1. Learn as much as you can during 3rd year. Read about your patients on UpToDate. (For shelf prep, I especially liked Pretest for peds, UWorld/MKSAP 5 for medicine, Pestana for surgery, Uwise for OB/Gyn)
2. UWorld (+UWSA test for extra questions)
3. Step Up to Medicine (IM)
4. MTB 2 (for IM) and 3 (for the non-IM subjects) (I didn't get very far with these... but lots of people like them).
I thought pretty much all the books I tried for dedicated step 2 prep were incomplete and I didn't retain much from them. They all had errors. Doing lots and lots of questions seemed most useful to me.
