I took mine over the summer, right after I had finished Ochem. I studied really hard for most of the summer, but totally slacked on the QR. I kicked a** on most of the sections but that one, and should have studied it more. Also, I should have done harder PAT stuff than just Topscore. I hear the Achiever is really good for PAT, although very difficult. Topscore is pretty good overall, but way to specific for questions.
For example, they don't really ask any thought-provoking questions, just kinda like, do you know this hormone and where it comes from? On the real test I could narrow down answer choices much more easily. Also on Gchem, it was WAY WAY too much math in TOPSCORE and Kaplan book. 90% of my questions were conceptual, like what is the 3-D structure of this molecule, or periodic trends, or what would an enzyme do to delta G....etc...
If I could take the test again, here are the 3 things I would do better...
1. Practice math way ahead of time, start practicing algebra again and going over probability and statistics. PRACTICE WITH A DRY ERASE BOARD A LOT!!!!!!!
2. Definitely do more conceptual understanding of Genchem
3. Look over different versions of PAT besides just TOPscore.
However, my other sections had pretty strong scores, so this is just what I would do. If your other scores need help start and work in the following order, because these are generally regarded as most important by admissions (I think)
1. Bio (read old bio books, I know it's boring and difficult, DO IT ANYWAYS!)
2. RC- Try and practice SAT type questions and learn to read quickly and efficiently.
3.OC
4. GC
5. QR
6. PAT
Schools where I am applying generally rank them in that order.