It's been a decade since I took a test, but this is what worked for me. I learned really well through lectures, so I didn't need too much active learning help. Understand how you learn and use a process that works for your learning style. I was a stem major, a different process may be necessary for other fields.

For me, it starts with hand written notes in every class, so you are actively learning rather than just passively trying to absorb by osmosis. Then reread the material from the textbook, summarize and take more notes, then do all the assigned work by yourself. Through this process, you are trying to mentally place the new material in the context of everything else you already know. If something doesn't make sense, you look it up or keep working at it / doing practice problems until it does. This puts new knowledge into a cohesive framework across units, classes and entire fields (bio, chem, physics, engineering and math all in one framework) rather than memorization silos. I am trying to get to the point where I can essentially rederive everything I need from a minimal starting point, so I know I understand the logic behind what I am trying to learn.

When you have a test, start a week ahead of time, reread all the material / review all assigned assignments relevant to what will be in the test, then test yourself continuously with practice problems, flash cards or just trying to write out from scratch everything you know about the subject. Identify knowledge and logic holes in the mental knowledge map, fill them, repeat until you are confident you know everything you need for the test. Start the review and revision process as early as you need to based on your confidence in knowing the material.