Anyone that has dreams to be a doctor has to first tackle the MCAT, the standardized test that anyone who wants to attend medical school needs to take and do very well on it.
I've tried to give you my two cents as someone that has taken the MCAT and gotten a 40 and then has taught prep courses and tutored students for the MCAT
Picking a test date: Nowadays the MCAT is offered many times a year, where as a few years ago students just had 2 choices, April or August. A test date between April -May is still ideal as it gives you an opportunity to take some more classes and also to take the test with enough time to get your score back and then have time to decide if you want to still apply to medical school. If that time of the year is not good for you, you can sign up earlier or later. If you sign up later then you may have to apply without knowing your score and once your score is released both you and the medical schools you applied to will know your score at the same time.
Pick a general route of study: Everyone student needs to decide if they want to take a prep course or just independent study. I would suggest taking a prep course if at all possible. Yes it costs a lot of money, but ideally you only want to take the MCAT once, if you have to take it again because of a low score, you will be at a big disadvantage when applying. There are 2 main prep courses offered, Kaplan and Princeton review. These 2 are pretty similar; one difference I have noticed is there is a difference between the study books they give you as part of the course. Kaplan's books are less detailed allowing you to add details as you study. Princeton Review's books are more text book like, with more details. This does not mean that Kaplan's books are not good enough; they do have a lot of material in them, just not to the same detail level as Princeton review. The other huge advantage of taking a prep course is that you will be given an opportunity to take practice exams. This is a big advantage.
Start studying early. I can understand it is very difficult to start studying for a test you may be taking 6 months later, especially with your other college classes, but it is important to start studying early if only once a week, just to get your brain comfortable with the books you are using.
Simplify the study material. Do not study from too many sources. Find a few study books you like, and use those to study the material. Most people use the prep course study books, which are very good. If you find one section to be difficult, then you should go to another source and add notes to your study books. This way you will have fewer books to read. The goal is to make sure you can re-read your notes and study books over and over. Repetition is key.
Practice Questions: Many students think they need to emphasize doing questions. While practice questions are important it is not as important as just studying. Once you have a good foundation of knowledge you should start doing practice questions. You have to make sure the time you spend doing questions is at least equal to the time you spend reviewing the questions and understanding why you got questions right and wrong. If you don't you will end up getting the same question wrong on the real test.
Practice exams: These are necessary. They will help you get acclimated with the test day and doing that many questions in a row. A few words of wisdom, try to do your practice exam at the same time/day as your real exam and try to treat it as the real test, the same break times, same breakfast, etc. These little things will make the real test day seem as routine.