"Seeing the BIG picture"
Another suggestion brought to my attention is the lack of seeing the "BIG picture". NBME questions just LOVE to integrate broad based concepts. One of the best integrating mechanisms is to listen to a GOOD LECTURE SERIES like Dr. Goljan's Audio for Step 1. He is a very entertaining and good gentleman. His audio notes are available in many places on the Internet. You can buy them, but I have heard that there is very little trouble to get them for free. Your other medical students probably have them too.
Draw large mental pictures for subjects like Biochemistry to grab the grand concepts. The Glycolysis and TCA cycle is the "Superhighway". Everything, all the reactions, attempt to feed into this "Superhighway" to make ATP. If you can draw the "Superhighway", then you can draw all the other reactions like the Pentose Phosphate Shunt, Fatty acid degradation, etc. and where it all feeds in. It really helps to form these mind maps. In fact, there are many good Biochemistry diagrams in a few textbooks that link all the reactions together. Find one and print it out! Actually, there are many computer programs that allow you to draw mental mind maps and connect concepts. It will end up being like a spider web to intertwine and capture and HOLD many more concepts. When you draw out the concepts, it REALLY WORKS in that it "sticks" to your brain!
See ya,
Tommyk