There are two general types of information for the CEH exam: that which you must memorize, and that which you should understand the concepts for and be able to reason your way through. As an example, you should be familiar enough with looking at code and script samples to be able to figure out (at a basic level) what is occurring with the exploit being presented. You do not need to be a rock-star C programmer or Perl scripter, but you should at least be able to read the code and make sense out of it. The same basic theory holds true for examining packet captures, IDS logs and web server logs. The courseware and the review guides will present several variations on this theme, so if you are not familiar with this type of analysis from your previous knowledge or work experience, you should be able to get up to speed in this area.
In regards to that information which you must really memorize, make use of the Cheat Sheet Exercises that complement Stephen DeFino’s official resource guide. There really is no better starting point out there for listing those items you must just flat out memorize.
In order to be fully prepared for this exam, and more importantly to become a competent and effective ethical hacker, spend plenty of time using Back Track 4 and the tools it contains.
Lastly, community sites such as The Ethical Hacker Network exist that can provide tremendous amounts of support, encouragement, and question answering.