I always find that the instrumental and when to use it are hard to translate from English. The dative can be a bit hard as well - but it's easier for German speakers or speakers of other Slavic languages as it's present there. Due to English's lack of an inherent case system except for mild accusative (He said...to him) which we get from German I think the entire concept makes you 'detach' your thinking from English grammar and just accept Russian declension for what it is.