1)... practice with genitive (='of') and dative (='to/for' or 'with/by' or following ἐν =in/on).

of the house, τῆς οἰκίας in the field,  ἐν τῷ ἀγρῷ on the sea,   [ἐν] τῇ θαλάττῃ of the city,   τῆς πόλεως with/by name,  [τῷ] ὀνόματι

for the master,  τῷ δεσπότῃ of the road,   τῆς ὁδοῦ for the child, τῷ or τῇ παιδὶ of the king, τοῦ βασιλέως

B. For the following (mostly from chh. 17-19):

1) First relearn--nom. and gen. with article for nouns; masc./fem./neut. nom. for adjj....(Find their place on the Noun Chart)

doctor, ὁ ἰατρός,  τοῦ ἰατροῦ law,  ὁ νόμος,  τοῦ νόμου enemy/hostile  ἐχθρός,  -ά,  -ον  ...or πολέμιος,  -α,  -ον opinion/judgment, ἡ γνώμη,  τῆς γνώμης anger, ἡ ὀργή,  τῆς ὀργῆς swift, ταχύς,  ταχεῖα,  ταχύ ship, ἡ ναῦς,  τῆς νεώς true, ἀληθής,  ἀληθές big, μέγας,  μεγάλη,  μέγα

priest, ὁ ἱερεύς,  τοῦ ἱερέως soul, ἡ ψυχή,  τῆς ψυχῆς money, τὸ ἀργύριον,  τοῦ ἀργυρίου sacrifice, ἡ θυσία,  τῆς θυσίας ...or τὸ ἱερεῖον,  τοῦ ἱερείου fear, ὁ φόβος,  τοῦ φόβου slow, βραδύς,  βραδεῖα,  βραδὺ island, ἡ νῆσος,  τῆς νήσου false, ψευδής,  ψευδές all, πᾶς,  πᾶσα,  πᾶν

2) Do the following drill with nom. and accusative:

for underlined phrase give the correct form, as either subject or object of the verb:

the doctor knows, ὁ ἱατρός

he knows the law, τὸν νόμον

we honor the priest, τὸν ἱερέα

Find the true soul,  τήν ἀληθῆ ψυχήν

anger is swift,   ὀργὴ ...ταχεῖα

we see the great ship  τὴν ναῦν μεγάλην

Now change all from singular to plural.  (You're on your own!)