You also must be able to apply the information even without immediate access to the printed material. One key method is to always extract the principle behind an idea. This is a lot easier to memorize than a bunch of details. The Sages compare it to carrying around paper money, versus large sacks of coins. This method also gives you a better basis to extrapolate and apply new ideas in the future.
Memorization is tremendously powerful.
Suppose you want to memorize all the bones in the human body. As you go through the body, each bone triggers a hint for the next. The mind likes mnemonic devices. Try to extract the essence of an idea, and record it in a catch-phrase that can be easily memorized. This way, rather than struggling to recall it from scratch, you'll be able to rebuild the entire idea from your catch-phrase.