My girlfriend thinks it's unbelievable that I've been in Germany (off and on) for well over a decade, and I've learned quite a lot of German, but I still can't get it right when it comes to mir vs mich, dir vs dich vs dein vs deine vs deins etc. I just can't get it. I know it's to do with nominative, accusative, dative and genetiv, and I can *almost* understand the ideas behind those concepts, but when it comes to real-world sentences I just fail miserably.
Is there anyone that can either point me in the direction of a book/course/video that explains it (especially for dummies) ? Or better still, manage to explain some simple[ton] rule that I can use?
Here are some example sentences (ignore any other errors, just focus on the relevant one):
Jemand hat dich/dir angerufen.
Bringst du mich/mir irgendwas?
Mir/Mich ist schlecht. (I know that one's Mir but I don't know why).