So far, I have been most impressed with this reference book:
I would highly recommend advancing to reference books written in Japanese and for Japanese readers after completing Tobira or something similar. I wish I’d thought to do this way earlier. Then again, kotowaza and kanyouku aren’t incredibly necessary to study alone. They can be learned in context. Perhaps I’m just weird. However, I think everyone could benefit from studying a collocations reference book. What do you all do at your upper intermediate/beginning advanced levels?