If you want to know how to learn German fast, I strongly suggest you begin with German cognates. You may not know this, but German and English share 60% of their vocabularies, so if you speak English, you’re already off to a great start with German.
Of course, one trick for anyone who wants to know how to learn German fast is to begin with cognates that overlap with the most commonly used vocabulary words in both languages.
Common noun cognates:
Common adjective cognates:
Common verb cognates:
Of course, this is just a tiny sample of cognates shared between English and German, but picking them up is an awesome approach for anyone who wants to know how to learn German fast.