Hi, Tihana. Wow, what an interesting question!

Five years ago, I brought a book for beginners (covering up to level B2) in which the seven cases are gradually introduced alongside usage examples in what the book considers as "practical" situations.

However, knowing theory is one thing, it's quite another to put it into practice. I try to watch, listen, or read something every day, in the hopes of approximating the exposure level that a native would have. This is the greatest contributor to learning those cases, in my opinion.

I also have a few language partners from the Balkans, as well as an italki profesor. Unfortunately, speaking remains my weakest area, as I don't practice it nearly as frequently as I do the other skills.

What are your methods for teaching padeže?

@Yifan Well, I tell them almost the same you explained. So, you have to learn grammar rules and after that try to speak as much as possible even if you are not sure is the case you used in right or wrong form. And listen, listen a lot and try to realize when or in what situations the case is used. Always write a notes when listen or read something that you don't understand so, later you can ask your language exchange partner or teacher to explain to you. And yes, try to find language exchange partner or few of them, it's so useful. You can ask them to practice one case in one lesson, next time another case etc.