Having rather recently taken that exam, I'd say know Blueprints inside and out. Knowing Pretest was pretty useful too, and I've found going through my Step 2 review books (First Aid and Boards and Wards) always is high yield for last minute shelf exam review as well. I used Appleton and Lange as well, but I don't think it helped that much on the exam, though it helped me process the Blueprints material in the first place, by having it in question format.
If I had to pick a topic that I should have known better, it would be failure to thrive/growth ******ation/premature puberty, which is lumped together as "endocrine", but that's just my opnion. However, as with all of the shelf exams, there's stuff on there (20%?) you can't really study for, since they mainly come clinical "common sense" which you've allegedly acquired during your rotation. I didn't think it was THAT hard, though I've heard many people say it's the hardest shelf. I think, in retrospect, it's the hardest rotation to STUDY because you have to cram about as much info as there is in internal medicine, in half the time.
Hope that helps. I wouldn't study any additional study materials than what I did in retrospect. Just know them well, and you'll be fine.