At OCS you'll take a bunch of exams. The most important thing for the exam is to be well-rested. People have fallen asleep during exams and gotten grades so low that they were eventually dropped. You'll get knowledge books that you'll use in class, during study time, and after lights. You can't use them at any other time unless specifically told to do so by an instructor. It's considered cheating if you do.
Academics and study-methods are my strong point. I'll share some of my study tips here:
Do not study every single detail. Make sure you study each chapter evenly. It's better to review each chapter lightly three times, then one or two chapters in detail, run out of time, and rush to study the others.
In class, come up with five study questions per chapter. This helps you pay attention in class, it helps you remember the material more, and helps you with a study review. When coming up with five questions, your brain is filtering more information than just the five questions, and assigns it importance. For example, if you had to memorize ten items of clothing in 1 minute, you might not recall the items as much as you would if you decided to rank the clothes from favorite to least favorite. Because when ranking them, you are focusing on specific things about those items and connecting them to things you like/dislike. If you get one or two other candidates to do the same, you can quiz each other after lights.
After lights, or in class, pick out sections that you think are important and determine how long it would take you to learn that material. I usually broke my chapters into chunks I thought I could study in 20 minutes. During study time, a lot of people would rifle through their books trying to figure out what to study. I already had sections picked out to focus on. This was especially helpful when we had random study time for 10 minutes here and there.
After the test, always go back to check your work and only change questions if it was obvious you read the question wrong, or if you now suddenly remember an answer that you didn't remember before. Don't change answers that you were unsure of before, and are unsure of later. Check your work to see if you had skipped a question and then filled in subsequent answers in the wrong spot. This tip isn't even OCS related. People fail exams all the time because of this.
During one of the exams, I nodded off for like 3 seconds. I got really freaked out and decided to work briskly through the exam in case it happened again. My goal was at least to get enough answers on paper before I feel asleep again. I didn't fall asleep, but I checked over my work carefully the second time around to make sure I didn't make mistakes.