The best source of materials to prepare you for the actual exam is the Association of American Medical Colleges (AAMC). You can purchase from them the MCAT Student Manual which has a thorough presentation of what the MCAT is about, sample questions with answers, how it is scored, etc. $20.
There are MCAT Practice Tests II, III, IV available, real exams already given. Questions on these and other such tests are prepared by professionals in test construction, not by amateurs like teachers and some review courses. The exam questions are copyrighted by AMCAS and no other organization may use them for test preparation courses. $20 each.
There is also a booklet, Scoring the MCAT Writing Sample: Examples of Writing Sample Responses and Explanation of Their Scores. $10.
Order from Association of American Medical Colleges, Department 66, Washington, DC 20055
202 828 0416 FAX: 202 828 1123
I haven't checked before writing this information, but it may well be on the AAMC web site:
www.aamc.org
It is never too early to start preparing for the Writing Sample and Verbal Reasoning test.
Test-taking skill, rather than subject matter knowledge, is 50% or more of earning
high scores, especially in Verbal Reasoning.
You have your work cut out for you.