der, die, das — review
You met der/die/das at A1 — at A2 the genders must sit, because every case form later builds on them. Drill them on the words A2 actually uses, and always learn a noun with its article and plural: die Wohnung (plural: die Wohnungen).
Tip
Word-building suffixes help: -ung, -heit, -keit → die; -chen → das; most words for male people → der. But test yourself — exceptions exist.