Russian cases: best resources
Hi! To be able to understand the Russian cases, you have to know exactly what meaning each case has and when we use them. It is also important to know which case we use with which preposition.
As for the resources, it depends on your level. If you need exercises for beginner level, you can visit this site: http://www.russianforfree.com/. As for the books, you can use "Russian Grammar in Exercises", "A Living Russian Grammar", "In Which Case", "Живая речь", etc.