Expanding my vocabulary

Hey guys,

I think I am at the point in my German studying where what I need the most is a lot of practice speaking with native speakers (easy, I love in Germany) and to expand my vocabulary a lot. I'm not really sure what the best approach to expanding my vocabulary is, so I am looking for suggestions.

My guess is that probably I need to make a real commitment to focused and diligent work with flashcards or flashcard software if I want to learn a lot of words quickly. Does anyone have any recommendations for what approach to follow here?

I have heard very good things about Anki, but I have struggled to find good vocabulary lists for it. Most of the ones I have found just contain the most frequent words in German or are targeted towards very early beginners, and since I haven't been able to figure out how to "remove" words I already know, this mostly just ends up being a giant pile of words I already know (not that helpful). Of course, I can build my own lists based on words I encounter reading and speaking with others, but building my own list is very time consuming and since I already barely have time for this commitment, I would prefer to use pre-made lists if they exist (especially if there are ones with pictures out there).

I remember when I was learning French that we would usually learn vocabulary words by "theme." This was nice, because while working on the words there was a little bit of an implicit clue to help figure them out if I didn't know, which I think helped me to learn more effectively. I think it also helped to really prepare for me to deal with a lot of situations by giving me most or all of the relevant words related to that situation. Does anyone know of any resources with vocabulary lists by theme (ideally with pictures -- or better yet, one big picture involving all of the words!) that is targeted at B2/C1-level students?

Maybe I just need a good textbook? Does anyone have any recommendations for a good textbook for vocabulary purposes?