The general advice that I give on preparing for the MCAT is to put time in studying for the exam up-front. You want to go into this process with the goal of taking the exam once, while it is okay to retake it, if needed. It is a costly exam, both of your time and financially; so, dedicating at least 500-600 hours to study content, and taking 10-12 practice exams will provide you with a solid study plan.
Another key point is to create a realistic study schedule that works well with your other commitments; classes, extracurriculars, labs, etc. Define your MCAT study days and break the hours up into manageable blocks. For example, if you dedicate an entire 8 hours to MCAT prep, break those up into 2-hour blocks. Take frequent breaks; maybe a 10-minute break after each hour or two, and a 30-minute break mid-way. During those breaks, do something creative and fun to engage the right side of your brain. You’ll come back refreshed and ready to begin your next section!