What will help you most, might not be improving your memory like you think but to better understand what memory is. The MO corse is great, when you know what memory is you can learn easier.
But if you do not want to spend the money here is what I suggest.
The most important thing is follow the study in 90 minute sections as Paul recommends. This is actually three 20 minute study periods (the outline is clear in the PR book). This is such an effective way to learn.
It aids memory, you stay fresh, you enjoy it more, its just great.
Use it as soon as you can. The knowledge that you have newly acquired.
Stay enthused
Be active in what you learn. It’s better to get upset with what you are strugling with than to gloss over in a superficial way hoping in some later date that you should be able to recall it. Enjoy the struggle, make it a challenge.
Ask yourself many questions.
Test yourself often
Quick review over old stuff, test yourself.
Know that there are no failures in learning.
Most importantly have confidence in your ability (that’s another reason why little tests that you create for yourself are great).
Keep track of your successes, especially the small things (far to easy not to)
Keep a journal of your own thoughts regarding how you are coping, what is effective, what causes you problems, what you find easy. (this will become a power house of information). Sometimes we need to have the same thought a few times before we act on it, so looking over a journal where you wrote down a solution to previous problem can aid you. Actually there are millions of ways this will become a power house of information, you will see.
I hope this is of some help. My grade improved, I feel like I do less work, I feel like I know the stuff better.
Good luck with your learning