*** Each person is different, but I think I can give a decent overview of what to do...
1) Get the Kaplan/PR/EK review books... it doesn't matter which one, jsut that you have a set - read them thoroughly and reread the chapters you don't know well twice (but only after a week interval). Take active notes of what you write as well for memorization purposes and for review.
2) For me, my orgo and gen chem were beasts (chem major), my bio and physics were weak. For physics, I reviewed
THE MCAT PHYSICS BOOK BY GARRETT BIEHLE - this book ROCKS!
I started getting 80%+'s on my physics questions (up from low 50's). Each chapter has ~60 questions on every topic that will be covered on the MCAT physics. Seriously, I credit my 11 and 12 on my practice tests to this book. If he made review books for bio and general chemistry I'd have a 36+ mcat.... i'm not kidding. Buffer your weak area with an entirely specialty book so that it becomes your strength!
3) Get the AAMC tests 3r-6r ... split up the cost with a friend so that the 3 tests are only 40 bucks. You can save as many practice tests as you want. Take the tests timed and in the exact order of the MCAT... do it in a place like the library.. or a place that is quiet, but not too quiet. I think Kap and PR tests are OK... good for timing issues etc and just making you think, but they generally do not have the trully conceptual questions that are all over the real MCAT.
4) Get your intro textbooks and reread select chapters ... that means GO OVER ELECTROCHEMISTRY AS MUCH AS YOU CAN!!! For me, I reread stuff about acetylcholine/parasymp/symp pathways/immunology/kidneys kidneys kidneys!/electrochem/acid base elquilibria ...
5) See if you can somehow find someone taking Kaplan and get the individual subject tests for areas of weakness. Kaplan is NOT NOT NOT NOT NOT NOT worth the money one bit.
6) Based on the last exam, TAKE PHYSIOLOGY!! I took anatomy, needless to say I was pissed at the biased questions... bailing out the baby-science bio majors yet again!
I think this method will get anyone a 30+. I make a high number of careless mistakes (3-7 / section), and I was still scoring quite high on the practice exams. The real exam went very well too.