Finding the best way to study is an ongoing process. It isn't something that can be left to the night before the test. You should be constantly improving your study skills to better understand what works (and what doesn't).
Learning how to study better helps avoid panic and frustration the next time a big test is coming up. After all, you are more likely to do well and be less stressed before a test when you have had time to properly review and practice the material!
Mastering effective study habits not only makes it easier to learn but will also help you get better grades in high school and post-secondary.