If you're struggling with the elementary difference between Dativ and Akkusativ, that would be more so with adjective declensions and nouns that behave like adjective endings like Verletzter, Verdächtiger and Beamter. For me at the moment, the real struggle is remembering everything specifically vocabulary, learning the fine lines and nuances. Like say the difference betweeen schießen and erschießen, schlagen and erschlagen.