I have no idea if kale helps you learn or not. I would be very surprised if it did, since I made up that idea when I was thinking of a good subject line for my email. Like my fictitious advice, the world is full of helpful study hints that may sound good, but for which there is little evidence. This is one of the reasons that you need to work to find methods that are effective for you (and drop the ones that aren't). Still, there are some things that we do know about learning from cognitive science. Unfortunately, like much basic research, what is born out in scientific studies often takes a long time to take hold in our everyday lives.
For example, there is strong scientific evidence that you will retain information longer if you approach your studying at regular intervals. It is better to study a little bit each day instead of trying to do it all the night before the exam. However, for many students cramming isn't just an emergency study strategy; it is the strategy of choice.
Cramming can work for short-term memory, but it is a poor option for actual learning. So try to plan your day so you can study a little bit for every course. Review what happened in class that day. Start the homework. Read. Ask yourself questions. Discuss the issues with a classmate. Go to office hours. In the end, I know that you will still cram before the exam. But even that will be more effective—and take less time—if you mete out your work in regular intervals. You might not notice for the exam, but you may be surprised what you retain moving forward. And that is a good thing, since learning is what we are all here to do.
Dr. Vanden Bout
P.S. Don't forget about sleep. It is good for learning, also. I've got the science to back it up. (Here is an article where UT researchers explain the importance of sleep in learning and memory and how you can be careful with sleep-depriving caffeine).