I know this may sound strange, but I have found that walking while memorizing with flashcards helps me tremendously. I can easily learn about 20 words per hour. What I do is first record a new word on a voice recorder in the new language, pause for a few seconds, then say the translation in my native language, and repeat this for up to 20 different new words. I keep my flashcards with me in the same order as the words on my recording so I can check the word if I am unsure of the spelling. When I go for a walk outside, usually to a quiet park, and just listen to my own voice speaking the new words and the translations. It really helps me to memorize words and there have been some studies that have backed this up: https://digest.bps.org.uk/2010/06/23/memory-performance-boosted-while-walking/