What would be the best way to learn the cases in german?

You need to write 5 mini exchanges with 5 of the 8 verbs listed below. your questions need to be written as inverted word order questions, in other words, as yes or no questions. the verb will be the first word in all of your questions. these mini exchanges will be in the 3rd person, using either he or she. here is an example with the verb phrase "freunde besuchen," meaning to visit friends. besucht er freunde? or besucht sie freunde? (does he visit friends? does she visit friends? ) ja, er besucht freunde. or ja, sie besucht freunde. (yes, he visits friends. yes, she visits friends.) you will either choose he or she for each conversation and you will not need to write the english translation. choose 5 of the following 8 verbs for your answers: reisen, kochen, schwimmen, kaufen, hausaufgaben machen, fuβball spielen, telefonieren or cds kaufen. i only need 2 examples , i'm not the best with german (don't use google translators or any translator, i dont want to get into trouble