I’m feeling overwhelmed by vocab learning. What’s the best way to go about it?

The best way to learn vocab is little and often. Having a notebook to write down any new words you come across helps you to have everything in one place. Every time you fill a page you could test yourself by reading, saying and then covering and writing English to German and German to English. Towards revision time if you have lots to learn in a short time from vocab lists, there are resources like Quizlet and Memrise which turn vocab lists into flashcards, quizzes and games which makes the process interactive and is much less time consuming than making flashcards manually. It’s important to remember also that the more you are exposed to a language, the more words you come across and the more instinctive you become by inferring meanings from the context, so it never hurts to do some extra reading, listening to music in German or watching TV or films in German.