I use Coffee Break German. It is a subscription, but podcasts are free. Have just done Season 1 lesson 17. There they introduce Dative for the first time, with only 3 prepositions, so not overwhelming, but it gives you an understanding of Dative with these 3 prepositions. I find it easier than all information at one. So now I know what the Dative case definate articles are in the Singular. Not even sure if there are plural ones, but will wait and see. So if anyone is interested, thye have a far more simple and gentle approach to pesky grammar and don't feel they have to give you the whole picture in one lump. My preferred way of learning. Earlier in the season they introduce other cases, as well as adjectives.