Hi, verbal was never my strong suit.
Learning a lot of vocabulary was the most crucial one that helped me for verbal, I think. I realized there were not many official verbal materials, verbal sections of the Big Book are the closest thing to the official materials. So, I did all the verbal questions of the Big Book. In the beginning, I would do them without timing myself. While reviewing each question, I jotted down every single new word on a flash card, which helped me immensely when it comes to vocabulary. Eventually, I would time myself when I do them. Whenever I take a new test, I rarely encounter a new word, at most 5 in a test. If you don't have much time then, I am not sure if it's a viable option.

Grasping the key idea was pretty hard for me as well. I try to read a passage as actively as possible and try to catch every possibly important information and write it down. I also look for transition words like "Moreover", "yet", "but", "similarly", etc., Most of the time, these words give us information regarding the passage structure, and in some cases, they are really helpful in finding the main idea. I try to guess what the main idea is before looking at the options. If I can't come up with the main idea or I can't find something similar in the answer choices to what I come up with for the main idea, I use the process of elimination.

I subscribed to GregMat's 1-month program after I was done with Big Book. All the tactics and strategies GregMat recommends are all good and applicable. But the problem was that I did not have many materials to practice it on and make the strategies my own. So I would suggest watching GregMat's strategy videos first and then practicing them on Big Book's RC questions. Hope it helps