I think the good thing that my book does when it comes to cases, is it has a a few paragraphs describing what the case is and when it's used. Then it shows the endings for nouns, followed by 10-15 examples of word's you know used in that case. Also, It doesn't introuduce them all at a time. So far I only know about Nominative, prepositional, and accustive, but I'm also only on the 6th lesson. In the first chapter, it doesn't even mention cases eventhough your using them.

Ch 4 - An intro to cases. Touches on Nominative and Prepositional
Ch 5 - Introduction to when the accustive case is used
Ch 6 - An intro to adjectives and their cases in Nominative form
Ch 7 - The rules for using the accustive case
Ch 8 - The Genetive case

And it goes on, but as you can see, you aren't given all the rules all at once, and your given plenty of time to let the idea's sink in before throwin a new case at you.