Use de for about two-thirds of Dutch nouns and het for the rest. There is no single rule that covers every case, so the most reliable approach is to learn each noun together with its article. However, you can use reliable patterns and categories to make a good guess most of the time.

Start with the reliable patterns. Diminutives always take het (het huisje, het meisje). Nouns ending in -ing, -heid, -teit, -tie, -schap, -isme, and -ment are almost always de (de regering, de vrijheid, de universiteit). Infinitives used as nouns take het (het lopen, het eten). Plural nouns always take de (de huizen, de meisjes). Most nouns for people take de (de man, de vrouw, de leraar), with a few exceptions like het kind and het meisje. Also, about 70% of nouns are de-words, so when you truly have to guess, de is the safer bet.

Accept the honest tradeoff. You will still meet exceptions. Some nouns are het-words for no obvious reason (het water, het boek, het huis), and a few can take both articles with a meaning change (de aarde = the earth, het aarde = the soil). Don't try to memorize a giant list of exceptions. Instead, treat the article as part of the word itself, like a spelling feature. When you learn a new noun, say it aloud with its article: "de tafel", "het raam". Write it that way in your vocabulary list, and use flashcards that test the article, not just the meaning.

Practical next steps. First, make a habit of noting the article every time you encounter a new noun. Second, use the patterns above as a quick check when you forget. Third, expose yourself to lots of simple Dutch input (children's books, news in simple Dutch, subtitled videos) so you hear correct articles in context. Fourth, when you write or speak, don't pause too long over de or het. A wrong article rarely blocks understanding, and fluency grows from using the language, not from perfect grammar. If you want structured practice, a resource like Dutch Fluency can help, but the core habit is yours: learn the noun and its article together, and let repetition do the rest.