If you can’t remember vocabulary words, try these strategies: Flashcards, word association, memory tricks (make up your own association), learning from the target language to English first and then from English to the target language, making up vocabulary sentences.
Flashcards
This is not a new trick but can be effective when used correctly. Get different colored flashcards. If your language has gender then use pink or red cards for feminine nouns and blue cards for masculine ones. Pick another color for neuter if needed. At the beginning of each chapter, put each new word or verb on a card (in the target language on one side, in English on the other).
Write as large as the card will permit. Count the cards and divide by the number of days you have to learn your new vocabulary. Fifty words divided by five days equals ten words/cards a day. Do your cards first thing in the morning and carry them with you throughout the day. When you have a five-minute break, do them again. Write when you can but do them orally when you can’t.
Do them again at night right before bed. In the morning do your old stack of ten cards and put any words you can’t remember into the new stack of ten. Keep reviewing old stacks of cards as often as possible. What you don’t remember goes in the active pile.