Read questions really carefully. On practice tests, I found myself missing easy questions because I misread and missed words like "not", "except", and "least likely". Watching out for these things saved me on test day.
Also, if you're not sure about a particular question and you feel like you may need several minutes to figure out the answer, mark the question and come back to it at the end. I sometimes found myself wasting time on questions that I would never get no matter how much time I spent on them, and this took away time from easy questions that I likely knew the answers to. Time management is really essential to doing well on the MCAT.
Lastly, take lots and lots of practice exams. I found that when I took the exam, most of the background knowledge that you needed was really surface-level. Half of doing well on the test is just becoming good at standardized tests and getting familiar with the format and the type of questions asked.