Thankfully, there are a lot of strategies out there for retaining meaningful information, practicing application of new skills and study review.
Take excellent notes by topic, sub topic, and most importantly, include examples. Pick a color to highlight each so that when reviewing your notes you can quickly make sense of them. As a rule of thumb, copy the framework or outline a professor uses during lecture and capture the examples they give to further your understanding. Their personal examples are a favorite for pop quizzes and short answers for tests.
Once a week, review your notes in every subject. This way you are checking your own understanding and reviewing any complicated concepts. Doing this once per week will greatly reduces the need to cram for final exams and gives you time to fill in any gaps in your understanding.
Use Office Hours:
A professor/teacher's office hours are there for a reason. Unfortunately not many people use them. Set yourself apart by dropping in regularly to establish a relationship, clarify concepts, and best of all -get tips of what to study for exams.
For tests with lots of memorization use flash cards. They actually work and after a first pass you will instantly know what to focus on.
For timed essays practice responding to a prompt under timed conditions. Start with a quick outline to frame your answer and practice to ensure you make the best use of the clock on exam day.
Hope this helps