Get an MCAT sample test book. About 1 week into your studying, go through an exam, taking as much time as you want, and answer every question. Then go back and score the test, looking at categories A, B and C separately. Reread those you missed to discover the silly tricks required to think like the people who prepare these tests. How well do you narrow down the answer.
Most people do better on the first impression.
Decide which is best for you. Some people are really good guessers - they actually may have seen the material but not have it in conscious memory. Good guessing will help your score, since a few extra correct answers may increase your score dramatically. Having taken the test the first time, study again for a couple of weeks. Get a good night's sleep the night before, get up early enough to have breakfast, spend 75 minutes sitting as if driving to Madison, then take the test exactly using the times in the test manual.