Make sure you buy the official Pearson Practice tests and when you take them, time yourself. Practice taking the full exam at home as it happens in real life with the break and everything. You can do this with Dr. Collins tests as well (however, since the Pearson tests are on the computer, it is more realistic). Time management is crucial. The content of the PCAT is difficult, but it's lack of time that kills you.
Kaplan is helpful for Biology particularly. I also used AudioLearn PCAT (you can find on Audible or iTunes), which is an audio book that gives a brief review of Bio and Chem (including O Chem). I listened to this constantly. In the car, in the shower, before bed, etc. I did so until I could recite it, simply because in the case something comes up on the actual test, I could recall the audio book and answer confidently.
Another good resource is YouTube. I watched all of "Crash Course: Chemistry," which is an extremely entertaining way to review concepts in Chemistry that you may need a refresher on. He also offers other Crash Courses such as Anatomy and Physiology and regular Biology, but I didn't have time before my PCAT to watch them all.
Likewise, I made notecards of all questions I got wrong from Dr. Collins/Kaplan/Pearson Tests and reviewed until I knew the answer by heart. This is key. You don't wanna get to the real test and realize you're about to make a mistake you already made at home during practice. I scored an 86 composite after studying for about 6 weeks, while working full time and raising a 3 year old. If I had had more time to devote to studying, I am sure I would have done better.
Most of all, just try to stay relaxed in the days before the test. Overthinking, second guessing yourself, and getting in your head, will also damage your score. It's important in the nights leading up to the test to get a lot of sleep, not just the night before. Eat a good breakfast before the test. It's long and you'll find yourself getting hungry halfway through. Also, remember to stay hydrated. Little things like this can make a huge difference.
Good luck!!